CN110388708B - Frequency controller of air conditioner cold and heat source two-stage water pump control system - Google Patents
Frequency controller of air conditioner cold and heat source two-stage water pump control system Download PDFInfo
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- CN110388708B CN110388708B CN201910672035.2A CN201910672035A CN110388708B CN 110388708 B CN110388708 B CN 110388708B CN 201910672035 A CN201910672035 A CN 201910672035A CN 110388708 B CN110388708 B CN 110388708B
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- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 title claims abstract description 79
- 238000006243 chemical reaction Methods 0.000 claims description 79
- 238000000034 method Methods 0.000 claims description 13
- 238000001914 filtration Methods 0.000 claims description 8
- 238000012216 screening Methods 0.000 claims description 6
- 230000000630 rising effect Effects 0.000 claims description 2
- 230000001174 ascending effect Effects 0.000 claims 1
- 230000002349 favourable effect Effects 0.000 abstract description 6
- 230000009286 beneficial effect Effects 0.000 abstract 1
- 238000004378 air conditioning Methods 0.000 description 13
- 230000001276 controlling effect Effects 0.000 description 6
- 230000001105 regulatory effect Effects 0.000 description 6
- 238000010586 diagram Methods 0.000 description 4
- 239000002699 waste material Substances 0.000 description 2
- 230000000694 effects Effects 0.000 description 1
- 238000004134 energy conservation Methods 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 230000008092 positive effect Effects 0.000 description 1
- 230000005855 radiation Effects 0.000 description 1
- 230000000087 stabilizing effect Effects 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
- F24F5/00—Air-conditioning systems or apparatus not covered by F24F1/00 or F24F3/00, e.g. using solar heat or combined with household units such as an oven or water heater
- F24F5/0003—Exclusively-fluid systems
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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
-
- 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
- F24F11/62—Control or safety arrangements characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
- F24F11/63—Electronic processing
- F24F11/64—Electronic processing using pre-stored data
-
- 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
- F24F11/84—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 valves
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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
- F24F11/88—Electrical aspects, e.g. circuits
-
- 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
- F24F2140/10—Pressure
- F24F2140/12—Heat-exchange fluid pressure
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- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02B—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
- Y02B30/00—Energy efficient heating, ventilation or air conditioning [HVAC]
- Y02B30/70—Efficient control or regulation technologies, e.g. for control of refrigerant flow, motor or heating
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Signal Processing (AREA)
- Physics & Mathematics (AREA)
- Fuzzy Systems (AREA)
- Mathematical Physics (AREA)
- Life Sciences & Earth Sciences (AREA)
- Sustainable Development (AREA)
- Air Conditioning Control Device (AREA)
Abstract
The invention relates to a frequency controller for an air conditioner cold and heat source secondary water pump control system with a plurality of branches, wherein the output of the secondary water pump is connected with the plurality of branches, the tail part of each branch is provided with a differential pressure controller and a tail bypass valve, the differential pressure controller is connected with the tail bypass valve, and the tail bypass valve is connected with the secondary water pump through the frequency controller; the tail pressure difference of each branch is completed by automatically controlling the opening of the tail bypass valve of the corresponding branch through the corresponding branch pressure difference controller, and when the opening of the tail bypass valve is fully closed or the opening of the tail bypass valve is overlarge, the frequency controller is required to adjust the frequency set value of the secondary water pump. The beneficial effects of the invention are as follows: the pressure or differential pressure of the least favorable branch can meet the requirement, so that the flow of cold and hot water of the least favorable branch can meet the requirement of cold and hot load; in addition, the pressure or differential pressure fluctuation of each branch is not large, so that the stability of the system is ensured; the rotating speed of the secondary water pump can be reduced as much as possible, so that the energy can be saved maximally.
Description
Technical Field
The invention belongs to the technical field of air conditioner control, and particularly relates to a frequency controller of an air conditioner cold and heat source secondary water pump control system.
Background
The air conditioning cold source or heat source is provided with cold water or hot water for the air conditioning tail end by a secondary water pump, the air conditioning tail end provides cold energy of cold water or heat of hot water for a room through direct radiation or coil pipes and the like so as to achieve the effect of adjusting room temperature, one air conditioning system is provided with a plurality of air conditioning tail ends, each air conditioning tail end is provided with a water valve for controlling the cold water or the hot water to enter the air conditioning tail end, the opening, closing or opening degree of the water valve is controlled by an air conditioning tail end controller according to the temperature difference value of the room, a plurality of branches are output by a common set of air conditioning system secondary water pump (1), each branch is provided with a plurality of air conditioning tail ends 2, the opening, closing or opening degree of the water valve of each air conditioning tail end is changed in working so that the flow of the cold water or the hot water is dynamically changed, and therefore the flow of the water of each branch is also dynamically changed, in order to ensure the normal operation of the air conditioning system, the stability of the water supply pressure or differential pressure of each branch is required, the stability of the pressure or differential pressure is realized by adjusting the opening of a pump outlet two-way regulating valve 5 or a pump outlet bypass valve 6 for a constant speed motor driven pump, the power supply frequency of a motor is required to be adjusted for a water pump 1 driven by a frequency converter, a controlled pressure or differential pressure feedback signal is from a pressure or differential pressure sensor 4 arranged at the tail part of the most unfavorable branch 3, the water resistance of each branch is inconsistent due to the fact that the pipe diameters or paths of the branches are different, the pressure or differential pressure of each branch is inconsistent, the branch with the minimum pressure or differential pressure is the most unfavorable branch, the pressure or differential pressure value of the other branches is satisfied, and the differential pressure system is controlled according to the most unfavorable branch, as shown in fig. 1. The pressure or differential pressure of the most unfavorable branch is regulated and stabilized according to the most unfavorable branch, the pressure or differential pressure of other branches outside the branch is higher than that of the most unfavorable branch, and the value is satisfactory, but the unstable water supply to the tail end of each air conditioner on the branch is caused due to no stabilizing measure, and meanwhile, energy waste is caused.
Disclosure of Invention
In order to solve the technical problems, the invention provides a frequency controller of an air conditioner cold and heat source secondary water pump control system.
The technical scheme adopted by the invention is as follows: a frequency controller of an air conditioner cold and heat source secondary water pump control system is characterized in that the output of a secondary water pump is connected with a plurality of branches, the tail of each branch is provided with a differential pressure controller and a tail bypass valve, the differential pressure controller is connected with the tail bypass valve, and the tail bypass valve is connected with the secondary water pump through the frequency controller.
Preferably, the frequency controller includes a filter, a minimum value selector, a maximum value selector, an up-conversion logic device, a down-conversion logic device and a frequency setting device, wherein the minimum value selector and the maximum value selector are connected with the filter, the up-conversion logic device and the down-conversion logic device are connected with the frequency setting device, and the up-conversion logic device and the down-conversion logic device are arranged between the up-conversion logic device and the down-conversion logic device.
Preferably, the opening of the tail bypass valve is provided with four threshold values, namely an up-conversion threshold, a stop down-conversion threshold and a down-conversion threshold from low to high.
Preferably, the tail part of the branch is also provided with a differential pressure sensor which is connected with a differential pressure controller.
Preferably, the secondary water pump is driven by a frequency converter.
Preferably, the frequency setter can be automatically selected or manually set.
A frequency control method for controlling tail differential pressure of a plurality of branches of a cold and heat source secondary water pump of an air conditioner comprises the following steps:
step one, the tail differential pressure of each branch is completed by automatically controlling the opening of the corresponding branch tail bypass valve through the corresponding branch differential pressure controller, when the opening of any tail bypass valve is fully closed, the step two is executed, and when the opening of any tail bypass valve is overlarge, the step three is executed;
screening the minimum valve opening, when the minimum valve opening is lower than the frequency raising threshold, the frequency sent to the water pump frequency converter by the frequency setter is given to rise according to the set slope, and when the minimum valve opening is higher than the frequency raising stopping threshold, the frequency setting is stopped;
screening the maximum valve opening, setting the frequency sent to the water pump frequency converter by the frequency setter to descend according to the set slope when the maximum valve opening is higher than the frequency-reducing threshold, and stopping descending when the maximum valve opening is smaller than the frequency-reducing threshold;
preferably, the branch circuit is cut off in advance before the second step and the third step are executed;
preferably, in the first step, the opening of the tail bypass valve is too large to exceed the frequency-reducing threshold.
Preferably, when the minimum valve opening is smaller than the frequency-raising threshold value, the output frequency-raising logic signal is in a high level, and when the minimum valve opening is higher than the frequency-raising threshold value, the output frequency-raising logic signal is in a low level;
and when the maximum valve opening is larger than the frequency-reducing threshold value. And when the maximum valve opening is lower than the frequency-reduction stopping threshold value, the output frequency-reduction logic signal is low.
Preferably, when the automatic selection signal is at a high level, if the up-conversion logic signal is at a high level, the frequency setting value is increased according to a slope, and if the up-conversion logic signal is at a low level, the frequency setting value is stopped from being increased and is maintained at a current value;
when the automatic selection signal is at a high level, if the frequency setting value is lowered according to the slope, and if the frequency setting value is lowered, the frequency setting value is stopped and kept at the current value;
when the automatic select signal is low, the frequency set point tracks the manual set point.
The invention has the advantages and positive effects that: the pressure or differential pressure of the least favorable branch can meet the requirement, so that the flow of cold and hot water of the least favorable branch can meet the requirement of cold and hot load; in addition, the pressure or differential pressure fluctuation of each branch is not large, so that the stability of the system is ensured; the rotating speed of the water pump can be reduced as much as possible, so that the energy can be saved maximally.
Drawings
FIG. 1 is a schematic diagram of differential pressure across the control system according to the most unfavorable leg;
FIG. 2 is a schematic diagram of a control system according to one embodiment of the invention;
FIG. 3 is a schematic diagram of a tail bypass valve opening threshold in accordance with one embodiment of the present invention;
fig. 4 is a schematic diagram of internal logic of a frequency controller according to an embodiment of the invention.
In the figure: 1-a secondary water pump; 2-an air-conditioning terminal; 3-branch; 4-differential pressure sensor; 5-two-way regulating valve; 6-pump outlet bypass valve; 7-a water diversion pipe; 8-a water collecting pipe; 9-tail bypass valve; 10-differential pressure controller; 20-frequency controller; 21-bypass valve opening; 22-branch excision; 23-up threshold; 24-stopping the frequency raising threshold; 25-stopping the frequency-reducing threshold; 26-a frequency-reducing threshold; 27, automatically selecting; 28 manual setting; 29-frequency set point; 30-a filter; 31-a minimum selector; 32-a maximum selector; 33-up logic; 34-down-conversion logic; 35-an up-conversion logic enabler; 36-a down-conversion logic enabler; 37-frequency setter; 40-opening of the bypass valve after filtering; 41-minimum valve opening; 42-maximum valve opening; 43-up logic signal; 44-down-converting the logic signal; 45-up enable logic signal; 46-down enable logic signal.
Description of the embodiments
An embodiment of the present invention is described below with reference to the accompanying drawings.
As shown in fig. 2, the present invention relates to a frequency controller of a control system of a cold and hot source secondary water pump of an air conditioner, wherein the secondary water pump 1 is driven by a frequency converter, a differential pressure sensor 4 is arranged at the tail of each branch, and a bypass valve 9 is arranged at the tail of each branch for improving the control characteristic. Specifically, the output of the secondary water pump 1 is connected with a plurality of branches 3, each branch 3 is provided with a plurality of air conditioner tail ends 2, the tail part of each branch 3 is provided with a differential pressure controller 10 and a tail bypass valve 9, the differential pressure controller 10 is used for controlling the tail differential pressure of the branch, the tail part of the branch is also provided with a differential pressure sensor 4, the differential pressure feedback is taken from the tail differential pressure sensor 4, and the output of the differential pressure controller 10 controls the tail bypass valve 9, so that the actual value of the tail differential pressure of the branch 3 tracks a set value; the differential pressure set value of the differential pressure controller 10 is confirmed in the system debugging stage, and the set value is kept unchanged after the system operates normally; the principle of determining the differential pressure set value is that the load of each branch is in a normal working condition, the differential pressure control arithmetic unit 10 is put into automation, and the differential pressure set value of each branch is regulated after the system is stabilized, so that the opening of the tail bypass valve of each branch is close; the tail bypass valve 9 is connected with the secondary water pump 1 through a frequency controller, and the secondary water pump 1 is driven by a frequency converter. As shown in fig. 3, the opening of the tail bypass valve 9 is provided with four thresholds, namely, an up-conversion threshold 23, a stop up-conversion threshold 24, a stop down-conversion threshold 25 and a down-conversion threshold 26 from low to high.
As shown in fig. 4, the frequency controller includes a filter 30, a minimum value selector 31, a maximum value selector 32, an up-conversion logic 33, a down-conversion logic 34, an up-conversion logic enabler 35, a down-conversion logic enabler 36, and a frequency setter 37, the minimum value selector 31 and the maximum value selector 32 are each connected to the filter 30, the up-conversion logic 33 and the down-conversion logic 34 are each connected to the frequency setter 37, and the up-conversion logic enabler 35 and the down-conversion logic enabler 36 are disposed between the up-conversion logic 33 and the down-conversion logic 34.
Filter 30: filtering the bypass valve opening of each branch, maintaining the stability of the operation of the controller, and forming a filtered bypass valve opening 40 by the bypass valve opening 21 through the filter;
minimum selector 31: comparing and selecting the minimum value for the opening degree of each branch valve after filtering, and outputting the valve opening degree of the branch cut 22 without participating in selection;
maximum selector 32: comparing and selecting the maximum value of the opening of each branch valve after filtering, and outputting the valve opening of the branch cut 22 without participating in selection;
up-conversion logic 33: if the minimum valve opening 41 output by the input minimum selector 31 is smaller than the frequency raising threshold 23, the frequency raising logic signal 43 is output to be high level, and is sent to the frequency setter 37 for setting the raising of the frequency 29, when the valve opening is higher than the frequency raising stopping threshold 24, the frequency raising logic signal 43 is output to be low level, so that the frequency raising output by the frequency setter (37) is stopped, and the frequency raising enabling logic signal 45 is working at high level;
the down-conversion logic 34: if the maximum valve opening 42 output by the input maximum selector 32 is larger than the frequency-reducing threshold 26, the frequency-reducing logic signal 44 is output to be high level, and is sent to the frequency setter 37 for setting the reduction of the frequency 29, when the valve opening is lower than the frequency-reducing stop threshold 25, the frequency-reducing logic signal 44 is output to be low level, so that the frequency-reducing of the frequency setter 37 is stopped, and the frequency-reducing enabling logic signal 46 is working at high level;
up-conversion logic enabler 35: the down-conversion logic signal 44 is inverted and then carries out logic AND operation with the automatic selection 27, and outputs an up-conversion enabling logic signal 45, and the up-conversion logic 33 works when the level is high;
the down logic enabler 36: the up-conversion logic signal 43 is inverted and then carries out logic AND operation with the automatic selection 27, and the down-conversion enabling logic signal 46 is output, so that the down-conversion logic 34 works when the level is high;
frequency setter 37: when the automatic selection signal 27 is at a high level, if the up-conversion logic signal 43 is at a high level, the frequency setting value 29 rises according to a certain time slope, and if the up-conversion logic signal 43 becomes at a low level, the rising of the frequency setting value 29 is stopped and kept at the current value; when the automatic selection signal 27 is at a high level, if the down-conversion logic signal 44 is at a high level, the frequency setting value 29 is lowered with a certain time slope, and if the down-conversion logic signal 44 becomes at a low level, the lowering of the frequency setting value 29 is stopped and kept at the current value; when the automatic selection signal 27 is low, the frequency setting 29 tracks the manual setting 28. The frequency setter 37 can be automatically selected or manually set.
The modules can be of conventional types in other existing circuits, and the maximum value selector and the minimum value selector can be of set selection modes and data selectors.
Good control requirements of a cold and heat source secondary system with a plurality of branches are as follows: 1) The pressure or differential pressure of the least favorable branch can meet the requirement, so that the flow of cold and hot water of the least favorable branch can meet the requirement of cold and hot load; 2) The pressure or differential pressure of each branch cannot fluctuate too much, so that the system is stable; 3) On the basis of meeting the two requirements, the rotating speed of the water pump is as small as possible so as to maximize energy conservation. In order to meet the above requirements, proper control is also needed, and the specific control method is as follows:
step one, the tail differential pressure of each branch is completed by automatically controlling the opening of the corresponding branch tail bypass valve through the corresponding branch differential pressure controller, when the opening of any tail bypass valve is fully closed, the step two is executed, and when the opening of any tail bypass valve is overlarge, the step three is executed;
screening the minimum valve opening, when the minimum valve opening is lower than the frequency raising threshold, the frequency sent to the water pump frequency converter by the frequency setter is given to rise according to the set slope, and when the minimum valve opening is higher than the frequency raising stopping threshold, the frequency setting is stopped;
screening the maximum valve opening, setting the frequency sent to the water pump frequency converter by the frequency setter to descend according to the set slope when the maximum valve opening is higher than the frequency-reducing threshold, and stopping descending when the maximum valve opening is smaller than the frequency-reducing threshold;
and carrying out branch cutting in advance before the second step and the third step, wherein the opening of the tail bypass valve in the first step is too large to exceed the frequency-reducing threshold.
Inputs to the frequency controller 20 include bypass valve opening 21, branch cut 22, boost threshold 23, stop boost threshold 24, stop downshift threshold 25, downshift threshold 26, automatic selection 27, manual set point 28.
Bypass valve opening 21: the numerical value is the opening setting value or the actual value of the tail bypass valve 9, and is one for each branch.
Branch excision 22: switching value, branch 3 not participating in control is cut off, and each branch is one.
The up-conversion threshold 23: and setting a value of a bypass valve opening value for increasing the frequency of the frequency converter.
Stopping the frequency up threshold 24: and setting a value of a bypass valve opening value for stopping the frequency rise of the frequency converter.
Stopping the frequency-reducing threshold 25: and setting a value of a bypass valve opening value for stopping reducing the frequency of the frequency converter.
The frequency-reducing threshold 26: the value is set to a bypass valve opening value for reducing the frequency of the inverter.
Automatic selection 27: the controller of the present invention is in an automatic state when the switching value is 1, and in a manual state when the switching value is 0.
Manual setting 28: when the numerical value is selected as the manual state by the controller, the output frequency set value is output according to the numerical value.
The output of the frequency controller is a frequency set value 29 and a numerical value, and the numerical value is sent to a driving frequency converter of the secondary water pump to control the rotating speed of the secondary water pump.
The present invention is further illustrated by the following specific examples.
Examples
The output of the secondary water pump 1 is connected with a plurality of branches 3, the tail part of each branch 3 is provided with a differential pressure controller 10 and a tail bypass valve 9, the differential pressure controller 10 is connected with the tail bypass valve 9, the tail part of the branch is also provided with a differential pressure sensor 4, the differential pressure sensor 4 is connected with the differential pressure controller 10, the tail bypass valve 9 is connected with the secondary water pump 1 through the frequency controller, and the secondary water pump 1 is driven by a frequency converter; the frequency controller comprises a filter 30, a minimum value selector 31, a maximum value selector 32, an up-conversion logic 33, a down-conversion logic 34, an up-conversion logic enabler 35, a down-conversion logic enabler 36 and a frequency setter 37, wherein the minimum value selector 31 and the maximum value selector 32 are connected with the filter 30, the up-conversion logic 33 and the down-conversion logic 34 are connected with the frequency setter 37, and the up-conversion logic enabler 35 and the down-conversion logic enabler 36 are arranged between the up-conversion logic 33 and the down-conversion logic 34; the opening of the tail bypass valve is provided with four threshold values, namely an up-conversion threshold 23, a stop up-conversion threshold 24, a stop down-conversion threshold 25 and a down-conversion threshold 26 from low to high.
As shown in fig. 2 and 4, the specific control method is as follows:
1. the controller 20 of the invention gives 29 signals to the frequency of the frequency converter of the water pump 1;
2. setting 4 threshold values for the opening of the tail bypass valve 9, wherein the threshold values are respectively as follows from low to high: the threshold 23, the threshold 24, the threshold 25, the threshold 26 are shown in figure 3;
3. the normal branch tail differential pressure is required to be completed by automatically controlling the opening degree of the bypass valve 9 by an external differential pressure controller 10;
4. when the opening of the tail bypass valve 9 is fully closed, the bypass valve 9 loses control over the tail differential pressure of the branch, in order to ensure the stability of the control over the tail differential pressure of the branch, the opening of the tail bypass valve 9 with the smallest opening of each branch is lower than the frequency raising threshold 23, the frequency given 29 of the frequency converter of the water pump 1 is sent to the frequency setting 29 of the frequency converter of the water pump 1 by the controller 20 according to the set slope to rise, the frequency of the frequency converter of the water pump 1 is gradually raised, the running speed of the water pump 1 is raised, thus the tail differential pressure tends to rise, and the tail differential pressure of the branch is regulated by the bypass valve 9, so that the external differential pressure controller 10 controls the opening of the tail bypass valve 9 to increase, and when the opening of the branch valve is larger than the frequency raising threshold 24, the frequency setting 29 is stopped.
5. When the opening of the bypass valve 9 is too large, the excessive water flowing through the bypass valve 9 wastes energy, and the motor frequency of the water pump 1 needs to be reduced, so that the opening of the valve 9 is smaller. When the opening of the tail bypass valve 9 with the largest opening of each branch is higher than the frequency-reducing threshold 26, the frequency setting 29 of the frequency converter of the water pump 1 is reduced according to the set slope by the controller 20, the frequency of the frequency converter is gradually reduced, the running speed of the water pump 1 is reduced, the tail differential pressure tends to be reduced, the tail differential pressure of the branch is regulated by the bypass valve 9, the external differential pressure controller 10 controls the opening of the tail bypass valve 9 to be reduced in order to keep the differential pressure stable, and when the opening of the branch valve is lower than the frequency-reducing threshold 25, the frequency setting 29 is reduced and stopped.
The foregoing describes one embodiment of the present invention in detail, but the description is only a preferred embodiment of the present invention and should not be construed as limiting the scope of the invention. All equivalent changes and modifications within the scope of the present invention are intended to be covered by the present invention.
Claims (10)
1. The utility model provides a cold and hot source second grade water pump control system's of air conditioner frequency controller, second grade water pump output is connected with a plurality of branches, its characterized in that: the tail part of each branch is provided with a differential pressure controller and a tail bypass valve, the differential pressure controller is connected with the tail bypass valve, and the tail bypass valve is connected with the secondary water pump through a frequency controller;
the frequency controller comprises a filter, a minimum value selector, a maximum value selector, an up-conversion logic device, a down-conversion logic device, an up-conversion logic enable device, a down-conversion logic enable device and a frequency setting device, wherein the minimum value selector and the maximum value selector are connected with the filter, the up-conversion logic device and the down-conversion logic device are connected with the frequency setting device, and the up-conversion logic enable device and the down-conversion logic enable device are arranged between the up-conversion logic device and the down-conversion logic device;
and (3) a filter: filtering the opening of the bypass valve of each branch, maintaining the stability of the operation of the controller, and forming the opening of the bypass valve after filtering through the filter;
minimum value selector: comparing and selecting the minimum value of the opening of each branch valve after filtering, and outputting the valve opening of branch cutting without participating in selection;
maximum value selector: comparing and selecting the opening of each branch valve after filtering to obtain the maximum value and outputting, wherein the opening of the valve cut off by the branch does not participate in selection;
the up-conversion logic: if the minimum valve opening output by the input minimum value selector is smaller than the frequency-raising threshold value, outputting an frequency-raising logic signal to be high level, sending the frequency-raising logic signal to the frequency setter for setting the frequency raising, and when the valve opening is higher than the frequency-raising stopping threshold value, outputting the frequency-raising logic signal to be low level, so that the frequency raising output by the frequency setter stops, and working when the frequency-raising enabling logic signal is high level;
the down-conversion logic: if the maximum valve opening output by the input maximum selector is larger than the frequency-reducing threshold value, outputting a frequency-reducing logic signal to be high level, sending the frequency-reducing logic signal to the frequency setter for setting frequency reduction, and when the valve opening is lower than the frequency-reducing stopping threshold value, outputting the frequency-reducing logic signal to be low level, so that the frequency reduction of the frequency setter is stopped, and working when the frequency-reducing enabling logic signal is high level;
up-conversion logic enabler: the down-conversion logic signal is inverted and then is subjected to logic AND operation with automatic selection, an up-conversion enabling logic signal is output, and the up-conversion logic works when the level is high;
the down-conversion logic enabler: the up-conversion logic signal is inverted and then is subjected to logic AND operation with automatic selection, a down-conversion enabling logic signal is output, and the down-conversion logic works when the down-conversion logic is at a high level.
2. The frequency controller of an air conditioner cold and heat source two-stage water pump control system according to claim 1, wherein: the opening of the tail bypass valve is provided with four threshold values, namely an ascending threshold value, a stopping descending threshold value and a descending threshold value from low to high.
3. The frequency controller of an air conditioner cold and heat source two-stage water pump control system according to claim 2, wherein: the tail part of the branch is also provided with a differential pressure sensor which is connected with the differential pressure controller.
4. The frequency controller of an air conditioner cold and heat source two-stage water pump control system according to claim 3, wherein: the secondary water pump is driven by a frequency converter.
5. The frequency controller of the air conditioner cold and heat source two-stage water pump control system according to claim 4, wherein: the frequency setter can be automatically selected or manually set.
6. The frequency control method for controlling the tail differential pressure of the air conditioner cold and heat source secondary water pump with a plurality of branches is based on the frequency controller of the air conditioner cold and heat source secondary water pump control system as set forth in any one of claims 1-5, and is characterized in that: the specific method comprises the following steps:
step one, the tail differential pressure of each branch is completed by automatically controlling the opening of the tail bypass valve of the corresponding branch through the corresponding branch differential pressure controller, when the opening of any tail bypass valve is fully closed, the step two is executed, and when the opening of any tail bypass valve is overlarge, the step three is executed;
screening the minimum valve opening, when the minimum valve opening is lower than the frequency raising threshold, raising the frequency sent to the water pump frequency converter by the frequency setter according to the set slope, and when the minimum valve opening is greater than the frequency raising stopping threshold, raising the frequency setting and stopping;
and thirdly, screening the maximum valve opening, when the maximum valve opening is higher than the frequency-reducing threshold, setting the frequency sent to the water pump frequency converter by the frequency setter to reduce according to the set slope, and when the maximum valve opening is smaller than the frequency-reducing threshold, stopping reducing the frequency setting.
7. The frequency control method for controlling tail differential pressure of the air conditioner cold and heat source two-stage water pump with a plurality of branches according to claim 6, wherein the frequency control method is characterized by comprising the following steps: and (3) performing branch circuit cutting in advance before executing the second step and the third step.
8. The frequency control method for controlling tail differential pressure of the air conditioner cold and heat source two-stage water pump with a plurality of branches according to claim 6, wherein the frequency control method is characterized by comprising the following steps: and in the first step, the opening of the tail bypass valve is too large to exceed the frequency-reducing threshold.
9. The frequency control method for controlling tail differential pressure of the air conditioner cold and heat source two-stage water pump with a plurality of branches according to claim 6, wherein the frequency control method is characterized by comprising the following steps: when the minimum valve opening is smaller than the frequency-raising threshold value, the output frequency-raising logic signal is in a high level, and when the minimum valve opening is higher than the frequency-raising stop threshold value, the output frequency-raising logic signal is in a low level;
and when the maximum valve opening is lower than the frequency-reduction threshold value, outputting a frequency-reduction logic signal as a low level.
10. The frequency control method for controlling tail differential pressure of the air conditioner cold and heat source two-stage water pump with a plurality of branches according to claim 9, wherein the frequency control method is characterized by comprising the following steps: when the automatic selection signal is at a high level, if the frequency-up logic signal is at a high level, the frequency setting value rises according to the slope, and if the frequency-up logic signal is at a low level, the frequency setting value stops rising and is kept at the current value;
when the automatic selection signal is at a high level, if the frequency setting value is lowered according to the slope, and if the frequency setting value is lowered, the frequency setting value is stopped and kept at the current value;
when the automatic select signal is low, the frequency set point tracks the manual set point.
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| CN111189103A (en) * | 2020-01-13 | 2020-05-22 | 欧贝多物联科技(嵊州)有限公司 | Intelligent bypass valve device |
| CN114484948B (en) * | 2021-12-23 | 2023-11-24 | 广东省建筑设计研究院有限公司 | Energy-saving multistage pump variable frequency linkage system |
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