CN115597133A - Central air-conditioning primary refrigerating pump frequency conversion control system and control method thereof - Google Patents

Central air-conditioning primary refrigerating pump frequency conversion control system and control method thereof Download PDF

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Publication number
CN115597133A
CN115597133A CN202211345866.7A CN202211345866A CN115597133A CN 115597133 A CN115597133 A CN 115597133A CN 202211345866 A CN202211345866 A CN 202211345866A CN 115597133 A CN115597133 A CN 115597133A
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China
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primary
water
temperature
return
refrigerating
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Inventor
高佳佳
刘雅琴
彭绮娴
汤立宽
熊琬钰
周传辉
李冠男
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Wuhan University of Science and Engineering WUSE
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Wuhan University of Science and Engineering WUSE
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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
    • F24F3/00—Air-conditioning systems in which conditioned primary air is supplied from one or more central stations to distributing units in the rooms or spaces where it may receive secondary treatment; Apparatus specially designed for such systems
    • 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
    • F24F11/85—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
    • 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
    • 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
    • F24F5/0007—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 cooling apparatus specially adapted for use in air-conditioning
    • 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
    • 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

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  • Engineering & Computer Science (AREA)
  • Chemical & Material Sciences (AREA)
  • Combustion & Propulsion (AREA)
  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Sustainable Development (AREA)
  • Signal Processing (AREA)
  • Physics & Mathematics (AREA)
  • Fuzzy Systems (AREA)
  • Mathematical Physics (AREA)
  • Air Conditioning Control Device (AREA)

Abstract

The invention discloses a frequency conversion control system of a primary refrigerating pump of a central air conditioner and a control method thereof, wherein the frequency conversion control system comprises a refrigerating host, the refrigerating host is sequentially connected with a primary water supply pipe, a secondary refrigerating pump, a secondary water supply pipe, a tail end air conditioning unit, a water return pipe and a primary refrigerating pump, and the primary refrigerating pump is connected with the refrigerating host to form a loop; the first temperature sensor and the second temperature sensor are electrically connected with the primary return water temperature optimization controller, and the primary return water temperature optimization controller, the third temperature sensor and the primary refrigerating pump frequency converter are electrically connected with the primary refrigerating pump frequency conversion controller. The invention uses the temperature sensor to measure the real-time temperature of the primary water supply pipe and the secondary water return pipe, and adjusts the running frequency of the frequency converter of the primary refrigerating pump on the premise of ensuring the stability and the reliability of the frequency conversion control of the primary refrigerating pump, so as to solve the unstable problem of the frequency conversion control of the primary refrigerating pump in the secondary pump system and further realize the energy consumption saving of the primary refrigerating pump.

Description

Central air conditioning primary refrigerating pump frequency conversion control system and control method thereof
Technical Field
The invention relates to the field of energy-saving control of air conditioners, in particular to a frequency conversion control system of a primary refrigeration pump of a central air conditioner and a control method thereof.
Background
Saving the energy consumption of building operation is an important way for reducing carbon emission. In the operation energy consumption of the building, the energy consumption ratio of the central air-conditioning system is more than 40 percent, and the central air-conditioning system is a main energy-saving object in the field of building energy conservation. At present, many energy-saving measures and control methods are provided for a central air-conditioning system, such as variable-frequency control of a refrigeration pump of a refrigeration station, variable-frequency control of a cooling pump, variable-frequency control of a cooling tower and the like.
The two-stage refrigerating pump system is usually adopted for large public buildings, parks, factories and the like due to factors such as long chilled water distribution distance, large branch resistance difference and the like. The secondary refrigerating pump system has more equipment relative to the primary refrigerating pump system, the system structure is more complex, and the operation control difficulty is higher. In the two-stage refrigerating pump system, the frequency conversion control is usually carried out on the secondary refrigerating pump, the primary refrigerating pump runs at a fixed frequency, but the energy consumption waste of the control mode is large. In recent years, designers have attempted to provide variable frequency control of the primary refrigeration pump of a two-stage refrigeration pump system, but there has been no good control method. The commonly used frequency conversion control of the primary refrigerating pump is controlled according to the size of the bypass water flow of the balance pipe between the primary system and the secondary system, namely the bypass water flow of the balance pipe is directly controlled. However, the water flow meter generally has low measurement accuracy and is susceptible to interference, and the measured value has large fluctuation, so that the method has poor stability and reliability in practical engineering application.
Disclosure of Invention
In order to overcome the technical problems, the invention aims to provide a primary refrigerating pump frequency conversion control system of a central air conditioner and a control method thereof, which reduce the energy consumption of the primary refrigerating pump on the premise of ensuring the stability of the frequency conversion control of the primary refrigerating pump, so as to solve the problem of instability of the frequency conversion control of the primary refrigerating pump in a secondary pump system and further realize the energy consumption saving of the primary refrigerating pump.
The invention provides the following technical scheme:
a frequency conversion control system for a primary refrigerating pump of a central air conditioner comprises a refrigerating host (1), wherein the refrigerating host (1) is sequentially connected with a primary water supply pipe (11), a secondary refrigerating pump (3), a secondary water supply pipe (13), a tail end air conditioning unit (4), a water return pipe and a primary refrigerating pump (2), and the primary refrigerating pump (2) is connected with the refrigerating host (1) to form a loop; a primary refrigerating pump frequency converter (9) is arranged on the primary refrigerating pump (2) and is used for carrying out frequency conversion adjustment on the primary refrigerating pump (2); a bypass is arranged at the front end of the primary water supply pipe (11) connected with the secondary freezing pump (3) and is a balance pipe (15), the balance pipe (15) is connected to the water return pipe, the water return pipe between the air conditioning unit (4) and the balance pipe (15) is a secondary water return pipe (14), and the water return pipe between the balance pipe (15) and the primary freezing pump (2) is a primary water return pipe (12);
a first temperature sensor (6) is arranged on the primary water supply pipe (11), a second temperature sensor (7) is arranged on the secondary water return pipe (14), a third temperature sensor (8) is arranged on the primary water return pipe (12), the first temperature sensor (6) and the second temperature sensor (7) are electrically connected with a primary water return temperature optimization controller (5), and the primary water return temperature optimization controller (5), the third temperature sensor (8) and a primary refrigerating pump frequency converter (9) are electrically connected with a primary refrigerating pump frequency conversion controller (10);
the first temperature sensor (6) and the second temperature sensor (7) respectively transmit temperature detection signals T in corresponding pipelines to the primary return water temperature optimization controller (5) in real time 1 And T 2 One of the primary return water temperature optimization controller (5)The secondary backwater temperature optimization calculation module is based on T 1 And T 2 Calculating the optimized set value T of the primary return water temperature 3,set And optimizing the primary return water temperature to a set value T 3,set Is transmitted to the primary refrigerating pump frequency conversion controller (10) through an electric signal, and a primary refrigerating pump frequency conversion control module of the primary refrigerating pump frequency conversion controller (10) receives a temperature signal T of the primary water return pipe (12) transmitted through the third temperature sensor (8) 3 And the primary return water temperature optimizing set value T 3,set And calculating a primary refrigerating pump frequency value, transmitting the primary refrigerating pump frequency value to a primary refrigerating frequency converter (9), and further controlling the primary refrigerating pump (2) to carry out frequency conversion according to the primary refrigerating pump frequency value.
In the above embodiment, the temperature sensor detects the temperature of each pipeline to calculate the primary return water temperature optimization setting value and the primary refrigeration pump frequency, and perform frequency conversion control of the primary refrigeration pump, and adjust the actual primary return water temperature in the primary return water pipe according to the setting value. The technical defects of high cost and poor precision of temperature adjustment of the traditional flowmeter are replaced. On the premise of ensuring the stability and the reliability of the frequency conversion control of the primary refrigerating pump, the energy consumption of the primary refrigerating pump is reduced, and the energy-saving purpose of reducing the energy consumption of the primary refrigerating pump is realized.
Wherein, the primary backwater temperature optimization calculation module is a program module or an operation module arranged in the primary backwater temperature optimization controller, the primary refrigerating pump frequency conversion control module is a program module or an operation module arranged in the primary refrigerating pump frequency conversion controller, and the primary backwater temperature optimization calculation module carries out the optimization according to T 1 And T 2 Calculating a primary return water temperature optimized set value; and the primary refrigerating pump frequency conversion control module is used for calculating the required primary refrigerating pump frequency value. The primary return water temperature optimization controller and the primary refrigerating pump frequency conversion controller can be selected from independent operation units, and can also be integrated and combined in one operation unit, wherein the operation unit can be selected from an existing single chip microcomputer, a PLC or a DDC controller.
The temperature sensor is used for collecting the water temperatures of a primary water supply pipe, a secondary water return pipe and a primary water return pipe to replace a flow meter to detect the water quantity of a balance pipe and adjust the frequency of a primary freezing pump by using flow, the temperature detection of the conventional temperature sensor is more accurate and reliable than that of the flow meter, the optimized temperature set value of the primary water return pipe is calculated by the primary water return temperature optimization controller, the frequency value of the primary freezing pump is calculated by the primary freezing pump frequency conversion controller according to the actually detected temperature of the primary water return pipe, the frequency signal of the frequency value of the primary freezing pump is transmitted to the primary freezing pump frequency converter, the water flow in the balance pipe is further adjusted, the temperature of the primary water return pipe is adjusted to the optimized temperature set value, and the purposes of accurately controlling the water flow in the balance pipe and saving energy are indirectly achieved through the temperature control of the primary water return pipe. And the bypass water quantity control target in the balance pipe is transmitted to the primary return water temperature optimization set value through the operation of the primary return water temperature optimization calculation module.
Further, the primary return water temperature optimization set value T 3,set The calculation formula is as follows:
T3，set＝KT1+(1-K)T@
in the above formula, K is the bypass water amount ratio of the balance pipe (15), i.e. the bypass water amount passing through the balance pipe (15) is the percentage of the water amount passing through the primary water supply pipe (11); and K is a self-defined target value, and the value range of K is greater than or equal to 0 and less than or equal to 0.3.
According to the embodiment, the K value is a weighted value and is also a control target value of the bypass water flow, the larger the K value is, the larger the bypass water flow is, the larger the redundancy quantity which can be obtained by the secondary pump is, but the larger the energy consumption waste of the corresponding primary pump is, and a worker can self-define the weighted value according to the actual production requirement on site. Setting K at the temperature value obtained by the formula, namely the optimal temperature set value of the primary water return pipe, and controlling the temperature of the primary water return pipe according to the value. The K value is set to be 0-0.3, so that a proper amount of bypass water is ensured, the stable water supply temperature of a system can be ensured, and the energy consumption of a primary pump can be reduced, wherein the K value is preferably 0.1, and when the K value is 0.1, namely the bypass water accounts for 10% of the total water, a certain amount of redundancy of a secondary pump can be ensured, the stable water supply temperature of the system is ensured, and the energy consumption waste of the primary pump can be reduced as much as possible.
Further, the primary return water temperature optimization set value T 3,set Has a certain range of 10-20 deg.C, when the calculated primary return water temperature optimum set value is less than 10 deg.C, T is 3,set =10 ℃, when the calculated primary backwater temperature optimal set value is larger than 20 ℃, then T 3,set ＝20℃。
The invention also provides a control method of the variable frequency control system, which comprises the following steps:
s1: presetting a bypass water quantity ratio K value of the balance pipe (15) according to the running state of the chilled water system; the first temperature sensor (6) and the second temperature sensor (7) respectively collect the temperatures of water in the primary water supply pipe (11) and the secondary water return pipe (12), and then transmit temperature signals to the primary water return temperature optimization controller (5);
s2: the primary return water temperature optimization controller (5) calculates a primary return water temperature optimization set value of the current system through a built-in primary return water temperature optimization calculation module, and sends the calculated primary return water temperature optimization set value to the primary refrigerating pump frequency conversion controller (10) through an electric signal;
s3: a primary refrigerating pump frequency conversion control module of the primary refrigerating pump frequency conversion controller (10) compares the received primary return water temperature optimization set value with the real-time primary return water temperature detected by the third temperature sensor (8), calculates the required primary refrigerating pump frequency according to the deviation value, and sends the required primary refrigerating pump frequency to the primary refrigerating pump frequency conversion device (9) through an electric signal to realize frequency conversion control of the primary refrigerating pump (2), and further adjusts the water flow in the balance pipe (15), so that the primary return water pipe temperature reaches the primary return water temperature optimization set value.
In the above embodiment, in the step S3, the purpose of accurately controlling the water flow rate in the balance pipe and saving energy is indirectly achieved through the temperature control of the primary water return pipe.
Further, the primary return water temperature optimization controller (5) adopts periodic calculation when calculating the primary return water temperature optimization set value.
In the above embodiment, the periodic calculation is to avoid the frequent entering of the primary return water temperature optimization controller (5) into the calculation.
Further, the period is 15 to 35 minutes.
In the embodiment, the shorter the period is, the more frequent the calculation of the primary return water temperature optimization controller (5) is, and the more accurate the bypass water amount control is, but the more frequent the corresponding primary pump frequency adjustment is, so that the system is not favorable for stable operation. The period is preferably 30 minutes, the accuracy of bypass water quantity control can be guaranteed, frequent adjustment of the frequency of the primary pump can be avoided, and the stability of system operation is guaranteed.
Compared with the prior art, the invention has the following beneficial effects:
the invention provides a frequency conversion control system and a control method of a primary refrigerating pump of a central air conditioner, which solve the technical problems of low measurement precision, high possibility of interference, large fluctuation of measured values and poor stability and reliability of a water flow meter in the prior art.
The control method of the invention has simpler steps, can conveniently calculate the better primary return water temperature optimized set value according to the calculation model of the primary return water temperature optimized set value, is suitable for installation and debugging of actual engineering, and can be widely applied to building air conditioning systems.
The invention has simple integral structure, convenient construction, lower cost of the temperature sensor than the flowmeter, more convenient installation than the flowmeter and lower total construction cost.
Drawings
FIG. 1 is a schematic diagram of an embodiment of the present invention;
the reference numbers in the figures are:
1. a refrigeration host; 2. a primary refrigeration pump; 3. a secondary refrigeration pump; 4. a terminal air conditioning unit; 5. a primary return water temperature optimizing controller; 6. a first temperature sensor; 7. a second temperature sensor; 8. a third temperature sensor; 9. a primary refrigeration pump frequency converter; 10. a primary refrigeration pump variable frequency controller; 11. a primary water supply pipe; 12. a primary water return pipe; 13. a secondary water supply pipe; 14. a secondary water return pipe; 15. and a balance tube.
Detailed Description
The present invention is described in detail below with reference to the following embodiments and the attached drawings, but it should be understood that the embodiments and the attached drawings are only used for the illustrative description of the present invention and do not limit the protection scope of the present invention in any way. All reasonable variations and combinations that fall within the spirit of the invention are intended to be within the scope of the invention.
The invention is further described below with reference to the accompanying drawings.
As shown in fig. 1, the control objects of the primary refrigerating pump frequency conversion control system of the central air-conditioning secondary pump include a refrigeration host 1, a primary refrigerating pump 2, a primary refrigerating pump frequency converter 9 for controlling the primary refrigerating pump 2 in a frequency conversion manner, a secondary refrigerating pump 3 and a terminal air-conditioning unit 4. Chilled water prepared by the refrigerating main machine 1 passes through the primary water supply pipe 11, one part of the chilled water enters the secondary refrigerating pump 3, the other part of the chilled water enters the balance pipe 15, the chilled water entering the secondary refrigerating pump 3 is pressurized by the secondary refrigerating pump 3 and then enters the tail end air conditioning unit 4 through the secondary water supply pipe 13 to exchange heat with circulating air, then is mixed with the chilled water by-passed by the balance pipe 15 through the secondary water return pipe 14, enters the primary water return pipe 12 again, and returns to the refrigerating main machine 1 after being pressurized by the primary refrigerating pump 2, and the chilled water circulation is completed.
The control device comprises a primary refrigerating pump frequency conversion device 9; a first temperature sensor 6 installed on the primary water supply pipe 11; a second temperature sensor 7 installed on the secondary water return pipe 14; a third temperature sensor 8 mounted on the primary water return pipe 12; a primary return water temperature optimizing controller 5 and a primary refrigerating pump frequency conversion controller 10. The primary refrigerating pump frequency conversion device 9 is used for carrying out frequency conversion control on the primary refrigerating pump 2 so as to adjust the bypass water flow of the balance pipe 15; the first temperature sensor 6 measures the water temperature in the primary water supply pipe 11 in real time and collects a real-time temperature signal; the second temperature sensor 7 measures the water temperature in the secondary water return pipe 14 in real time and collects real-time temperature signals; the third temperature sensor 8 measures the water temperature in the primary water return pipe 12 in real time and collects real-time temperature signals; real-time temperature signals collected by the first temperature sensor 6 and the second temperature sensor 7 are transmitted to the primary return water temperature optimization controller 5, and the primary return water temperature optimization controller 5 is electrically connected with the primary refrigeration pump frequency conversion controller 10; the primary return water temperature optimization controller 5 calculates a primary return water temperature optimization set value according to the collected temperature signal, and transmits the primary return water temperature optimization set value signal to the primary cold pump variable frequency controller 10; the third temperature sensor 8 transmits the measured water temperature signal in the primary water return pipe 12 to the primary refrigeration pump frequency conversion controller 10; the primary refrigeration pump frequency conversion controller 10 takes the primary return water temperature optimization set value as a target, calculates the operation frequency of the primary refrigeration pump 2 according to the real-time temperature of the primary return water pipe 12, namely, a temperature value signal returned by the third temperature sensor 8, outputs the calculated frequency electric signal to the primary refrigeration pump frequency converter 9, controls the operation frequency of the primary refrigeration pump 2, and further adjusts the temperature of the primary return water pipe 12 to the primary return water temperature optimization set value by adjusting the bypass water flow of the balance pipe 15. The accurate control of the water flow in the balance pipe and the variable-frequency energy-saving operation control of the primary refrigerating pump are indirectly achieved through the control of the primary water return temperature, namely the temperature control of the primary water return pipe 12.
The primary return water temperature optimization controller 5 and the primary refrigerating pump frequency conversion controller 10 are respectively internally provided with a primary return water temperature optimization calculation module and a primary refrigerating pump frequency conversion control module, and the two modules can also be internally arranged in one control module, namely the primary return water temperature optimization controller and the primary refrigerating pump frequency conversion controller are combined to form one control module.
The control method of the frequency conversion control system of the primary refrigerating pump of the central air conditioner comprises the following steps:
s1: presetting a bypass water quantity ratio K value of the balance pipe 15 according to the running state of the chilled water system; the first temperature sensor 6 and the second temperature sensor 7 respectively collect the temperature of water in the primary water supply pipe 11 and the secondary water return pipe 12, and then transmit temperature signals to the primary water return temperature optimization controller 5;
s2: the primary return water temperature optimization controller 5 calculates a primary return water temperature optimization setting value of the current system through a built-in primary return water temperature optimization calculation module, and sends the calculated primary return water temperature optimization setting value to the primary refrigerating pump frequency conversion controller 10 through an electric signal;
s3: the primary refrigerating pump frequency conversion control module of the primary refrigerating pump frequency conversion controller 10 compares the received primary return water temperature optimization setting value with the real-time primary return water temperature detected by the third temperature sensor 8, calculates the required primary refrigerating pump frequency according to the deviation value, and sends the primary refrigerating pump frequency conversion control value to the primary refrigerating pump frequency conversion device 9 through an electric signal, so that the frequency conversion control of the primary refrigerating pump 2 is realized, and further the water flow in the balance pipe 15 is adjusted, so that the primary return water pipe temperature reaches the primary return water temperature optimization setting value.
According to the control method, the aims of accurately controlling the water flow in the balance pipe and saving energy are indirectly achieved through the temperature control of the primary water return pipe.
In the control method, a primary return water temperature optimization algorithm is executed by a primary return water temperature optimization calculation module; the calculation of the frequency of the primary refrigerating pump is operated by a primary refrigerating pump variable frequency control module. The primary return water temperature optimization controller 5 adopts periodic calculation when calculating the primary return water temperature optimization set value, and the calculation period is preferably 30 minutes.
The calculation formula of the primary return water temperature optimization set value is as follows:
T3，set＝KT1+(1-K)T2
in the above formula, K is the bypass water amount ratio of the balance pipe 15, i.e. the percentage of the bypass water amount in the total water amount of the primary system, is a user-defined target value, and the value is greater than or equal to 0 and less than or equal to 0.3; t is 1 The primary water supply temperature; t is 2 The secondary return water temperature; t is a unit of 3,set Is a better primary return water temperature set value, wherein T 1 、T 2 And T 3,set The units of (A) are all.
Optimized set value T of primary return water temperature 3,set Has a certain range, such as 10-20 ℃, when the calculated primary return water temperature optimized set value is less than 10 ℃, then T 3,set =10 ℃, when the calculated primary backwater temperature optimal set value is larger than 20 ℃, then T 3,set ＝20℃。
The primary variable frequency control module in the primary variable frequency controller 10 may employ a PID control algorithm.
Example one
The invention provides a primary water supply temperature T of a primary refrigerating pump variable frequency control system of a central air conditioner 1 Keeping the temperature, such as 7 ℃, of the secondary freezing water pump 3, controlling the temperature difference of the supply water and the return water of the secondary loop to be constant through frequency conversion regulation, and when the load of the air conditioner unit 4 changes, regulating the operating frequency of the secondary freezing pump 3 to maintain the temperature T of the secondary return water 2 Keeping the temperature constant, such as 12 ℃, at the moment, the proportion of the bypass water in the balance pipe 15 will increase or decrease and deviate from the K value set by the user, the K value is set to be 0.1, and the corresponding primary return water temperature T 3 Will change and deviate from the primary backwater optimized set value T 3,set Calculating T by the primary return water temperature optimizing controller 5 3,set The temperature is 11.5 ℃, the primary refrigerating pump frequency conversion controller 10 adopts PID algorithm to calculate the running frequency of the primary refrigerating pump 2, sends a frequency signal to the primary refrigerating pump frequency converter 9, executes frequency conversion adjustment, changes the water quantity of a primary refrigerating water system, further changes the bypass water quantity in the balance pipe 15, and when the primary return water temperature T is higher than the primary return water temperature T 3 Is controlled at a set value T 3,set At this time, the bypass water amount ratio in the balance pipe 15 is also maintained at the set value K.
Example two
The water quantity of the secondary chilled water system is kept unchanged, and when the primary water supply temperature T of the variable frequency control system provided by the invention 1 For example, when 7 ℃ is changed or the load of the air conditioning unit 4 is changed, the secondary water return temperature T 2 Will also change, the corresponding primary backwater temperature T 3 The water quantity of the secondary chilled water system is kept constant, the proportion of the bypass water quantity in the balance pipe 15 is kept constant at the K value, and the primary return water temperature optimization setting calculated by the primary return water temperature optimization controller 5 is changedConstant value T 3,set Is changed along with the change and is compared with the actual primary return water temperature T 3 And the frequency value of the primary refrigerating pump operation output by the primary refrigerating pump variable-frequency controller 10 is not changed.
In summary, in the control method of the variable frequency control system, only when the secondary chilled water flow changes, the bypass water ratio in the balance pipe 15 changes, the operation frequency of the primary chilling pump is adjusted accordingly, and the bypass water ratio in the balance pipe 15 is maintained unchanged through the control of the primary return water temperature.
The invention provides a frequency conversion control system and a frequency conversion control method for a primary refrigerating pump of a central air conditioner, wherein a temperature sensor is used for measuring the temperature of a primary water supply pipe, a secondary water return pipe and a primary water return pipe, the precision and the stability of the temperature sensor are higher than those of a flow meter, the purchasing cost of the temperature sensor is lower than that of the flow meter, and the temperature is adopted as a control target and is more stable and reliable than the flow as the control target, the control precision is higher, and the cost is lower.
The above examples are merely preferred embodiments of the present invention, and the scope of the present invention is not limited to the above examples. All technical schemes belonging to the idea of the invention belong to the protection scope of the invention. It should be noted that modifications and adaptations to those skilled in the art without departing from the principles of the present invention should also be considered as within the scope of the present invention.

Claims (6)

1. A frequency conversion control system of a primary refrigerating pump of a central air conditioner comprises a refrigerating host (1), wherein the refrigerating host (1) is sequentially connected with a primary water supply pipe (11), a secondary refrigerating pump (3), a secondary water supply pipe (13), a tail end air conditioning unit (4), a water return pipe and a primary refrigerating pump (2), and the primary refrigerating pump (2) is connected with the refrigerating host (1) to form a loop; a primary refrigerating pump frequency converter (9) is arranged on the primary refrigerating pump (2) and is used for carrying out frequency conversion adjustment on the primary refrigerating pump (2); the front end that primary water supply pipe (11) and secondary refrigeration pump (3) are connected is equipped with the bypass, promptly balancing pipe (15), balancing pipe (15) are connected to wet return, air conditioning unit (4) with wet return between balancing pipe (15) be secondary wet return (14), wet return between balancing pipe (15) and primary refrigeration pump (2) is promptly wet return (12), its characterized in that:
a first temperature sensor (6) is arranged on the primary water supply pipe (11), a second temperature sensor (7) is arranged on the secondary water return pipe (14), a third temperature sensor (8) is arranged on the primary water return pipe (12), the first temperature sensor (6) and the second temperature sensor (7) are electrically connected with the primary water return temperature optimization controller (5), and the primary water return temperature optimization controller (5), the third temperature sensor (8) and the primary refrigerating pump frequency converter (9) are electrically connected with the primary refrigerating pump frequency conversion controller (10);
the first temperature sensor (6) and the second temperature sensor (7) respectively transmit temperature detection signals T in corresponding pipelines to the primary return water temperature optimization controller (5) in real time 1 And T 2 The primary return water temperature optimization calculation module of the primary return water temperature optimization controller (5) calculates the primary return water temperature according to T 1 And T 2 Calculating the optimized set value T of the primary return water temperature 3,set And optimizing the primary return water temperature to a set value T 3,set Is transmitted to the primary refrigerating pump frequency conversion controller (10) through an electric signal, and a primary refrigerating pump frequency conversion control module of the primary refrigerating pump frequency conversion controller (10) receives a temperature signal T of the primary water return pipe (12) transmitted through the third temperature sensor (8) 3 And the primary return water temperature optimizing set value T 3,set And calculating a primary refrigerating pump frequency value, transmitting the primary refrigerating pump frequency value to a primary refrigerating frequency converter (9), and further controlling the primary refrigerating pump (2) to carry out frequency conversion according to the primary refrigerating pump frequency value.
2. The variable frequency control system of claim 1, wherein: the primary backwater temperature optimizing set value T 3,set The calculation formula is as follows:
T 3，set ＝KT 1 +(1-K)T 2
in the above formula, K is the bypass water amount ratio of the balance pipe (15), i.e. the bypass water amount passing through the balance pipe (15) is the percentage of the water amount passing through the primary water supply pipe (11); and K is a self-defined target value, and the value range of K is greater than or equal to 0 and less than or equal to 0.3.
3. The variable frequency control system of claim 2, wherein: the primary return water temperature optimizing set value T 3,set Has a certain range of 10-20 deg.C, when the calculated primary return water temperature optimum set value is less than 10 deg.C, T is 3,set =10 ℃, when the calculated primary backwater temperature optimal set value is larger than 20 ℃, then T 3,set ＝20℃。
4. The control method of any one of the variable frequency control systems according to claims 1 to 3, characterized in that: the method comprises the following steps:
s1: presetting a bypass water quantity ratio K value of the balance pipe (15) according to the running state of the chilled water system; the first temperature sensor (6) and the second temperature sensor (7) respectively collect the temperature of water in the primary water supply pipe (11) and the secondary water return pipe (12), and then transmit temperature signals to the primary water return temperature optimization controller (5);
s2: the primary return water temperature optimization controller (5) calculates a primary return water temperature optimization setting value of the current system through a built-in primary return water temperature optimization calculation module, and sends the calculated primary return water temperature optimization setting value to the primary refrigerating pump frequency conversion controller (10) through an electric signal;
s3: and a primary refrigerating pump frequency conversion control module of the primary refrigerating pump frequency conversion controller (10) compares the received primary return water temperature optimized set value with the real-time primary return water temperature detected by the third temperature sensor (8), calculates the required primary refrigerating pump frequency according to the deviation value, and sends the required primary refrigerating pump frequency to the primary refrigerating pump frequency conversion device (9) through an electric signal to realize frequency conversion control of the primary refrigerating pump (2), so as to adjust the water flow in the balance pipe (15) and enable the primary return water pipe temperature to reach the primary return water temperature optimized set value.
5. The control method according to claim 4, characterized in that: and the primary return water temperature optimization controller (5) adopts periodic calculation when calculating the primary return water temperature optimization set value.
6. The control method according to claim 5, characterized in that: the period is 15 to 35 minutes.
CN202211345866.7A 2022-10-31 2022-10-31 Central air-conditioning primary refrigerating pump frequency conversion control system and control method thereof Pending CN115597133A (en)

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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117346305A (en) * 2023-12-06 2024-01-05 广东蘑菇物联科技有限公司 Temperature difference control method and device for cryopump, storage medium and computer equipment

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN117346305A (en) * 2023-12-06 2024-01-05 广东蘑菇物联科技有限公司 Temperature difference control method and device for cryopump, storage medium and computer equipment
CN117346305B (en) * 2023-12-06 2024-03-08 广东蘑菇物联科技有限公司 Temperature difference control method and device for cryopump, storage medium and computer equipment

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