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CN114440409A - Self-adaptive energy-saving control method for central air-conditioning system - Google Patents

Self-adaptive energy-saving control method for central air-conditioning system Download PDF

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CN114440409A
CN114440409A CN202210027528.2A CN202210027528A CN114440409A CN 114440409 A CN114440409 A CN 114440409A CN 202210027528 A CN202210027528 A CN 202210027528A CN 114440409 A CN114440409 A CN 114440409A
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陈鹏
吴佳帧
王德民
刘松
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China Design Group Co Ltd
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    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00Control or safety arrangements
    • F24F11/50Control or safety arrangements characterised by user interfaces or communication
    • F24F11/54Control or safety arrangements characterised by user interfaces or communication using one central controller connected to several sub-controllers
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00Control or safety arrangements
    • F24F11/50Control or safety arrangements characterised by user interfaces or communication
    • F24F11/61Control or safety arrangements characterised by user interfaces or communication using timers
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00Control or safety arrangements
    • F24F11/62Control or safety arrangements characterised by the type of control or by internal processing, e.g. using fuzzy logic, adaptive control or estimation of values
    • F24F11/63Electronic processing
    • F24F11/64Electronic processing using pre-stored data
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00Control or safety arrangements
    • F24F11/70Control systems characterised by their outputs; Constructional details thereof
    • F24F11/72Control systems characterised by their outputs; Constructional details thereof for controlling the supply of treated air, e.g. its pressure
    • F24F11/74Control systems characterised by their outputs; Constructional details thereof for controlling the supply of treated air, e.g. its pressure for controlling air flow rate or air velocity
    • F24F11/77Control systems characterised by their outputs; Constructional details thereof for controlling the supply of treated air, e.g. its pressure for controlling air flow rate or air velocity by controlling the speed of ventilators
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00Control or safety arrangements
    • F24F11/70Control systems characterised by their outputs; Constructional details thereof
    • F24F11/80Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air
    • F24F11/83Control 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
    • F24F11/84Control 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
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F11/00Control or safety arrangements
    • F24F11/70Control systems characterised by their outputs; Constructional details thereof
    • F24F11/80Control systems characterised by their outputs; Constructional details thereof for controlling the temperature of the supplied air
    • F24F11/83Control 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
    • F24F11/85Control 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
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F2110/00Control inputs relating to air properties
    • F24F2110/10Temperature
    • F24F2110/12Temperature of the outside air
    • FMECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F24HEATING; RANGES; VENTILATING
    • F24FAIR-CONDITIONING; AIR-HUMIDIFICATION; VENTILATION; USE OF AIR CURRENTS FOR SCREENING
    • F24F2140/00Control inputs relating to system states
    • F24F2140/20Heat-exchange fluid temperature
    • YGENERAL 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
    • Y02TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02BCLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO BUILDINGS, e.g. HOUSING, HOUSE APPLIANCES OR RELATED END-USER APPLICATIONS
    • Y02B30/00Energy efficient heating, ventilation or air conditioning [HVAC]
    • Y02B30/70Efficient 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)
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  • Mechanical Engineering (AREA)
  • General Engineering & Computer Science (AREA)
  • Physics & Mathematics (AREA)
  • Human Computer Interaction (AREA)
  • Signal Processing (AREA)
  • Fluid Mechanics (AREA)
  • Fuzzy Systems (AREA)
  • Mathematical Physics (AREA)
  • Air Conditioning Control Device (AREA)

Abstract

The invention discloses a self-adaptive energy-saving control method of a central air-conditioning system, which comprises the steps of monitoring and calculating the total cooling capacity of the air-conditioning system in real time, and adjusting the number of air-conditioning units according to the value of the total cooling capacity; then adjusting the frequency of a freezing water pump, the frequency of a cooling water pump and the frequency of a cooling tower fan through a self-adaptive PID fuzzy controller according to the temperature difference of the supply and return water of the freezing water, the temperature difference of the supply and return water of the cooling water, the water outlet temperature of the cooling tower and the temperature difference of an outdoor wet bulb; in addition, the rotating speed of the fan is adjusted according to the air supply quantity, and the fresh air ratio is adjusted according to seasons; the invention adopts a self-adaptive fuzzy PID control mode, avoids the control instability of the central air-conditioning system caused by the characteristics of nonlinearity, large hysteresis, large inertia, time-varying property, strong coupling and the like, and provides a full-flow control strategy of the central air-conditioning system, so that the central air-conditioning system can run more energy-saving.

Description

Self-adaptive energy-saving control method for central air-conditioning system
Technical Field
The invention belongs to the field of energy-saving optimization control of a central air conditioner, and particularly relates to a self-adaptive energy-saving control method of a central air conditioning system.
Background
The energy consumption of the central air-conditioning system accounts for a large proportion of the energy consumption of buildings, and the automatic control method of the central air-conditioning system not only influences the environmental parameters such as indoor temperature and humidity, but also directly influences the energy consumption of the central air-conditioning system. Meanwhile, most central air-conditioning systems are designed according to the maximum load of a building, the running time frequency of the system in a full-load state is very small, most of the running time is under partial load, and the central air-conditioning system has a large energy-saving space.
In the current central air-conditioning system, various control systems taking a PID control algorithm as a core are generally applied, but because the central air-conditioning system is a complex system with nonlinearity, large hysteresis, large inertia, time-varying property and strong coupling, and a mathematical model of a controlled object is constantly changed, only the PID control is adopted, and an ideal control effect cannot be obtained.
Meanwhile, the system energy-saving operation of the central air conditioner needs to consider global optimization under partial load, and ideal energy-saving effect cannot be achieved only by optimally controlling a certain component. Therefore, an adaptive energy-saving control method for a central air-conditioning system aiming at multi-objective optimization is an effective means for solving the problems.
Disclosure of Invention
In order to solve the problem that the traditional PID control method cannot achieve an ideal control effect, the invention provides a self-adaptive energy-saving control method for a central air-conditioning system.
The technical scheme adopted by the invention is as follows: a self-adaptive energy-saving control method for a central air-conditioning system comprises the following steps:
s101, acquiring initial values of a chilled water end, a cooling water end and a fan end of a central air conditioner;
s102, monitoring and calculating the total cooling capacity Q of the air conditioning system in real time, and adjusting the number of air conditioning units according to the value of the total cooling capacity Q;
s103, determining the supply and return water temperature t of the chilled waterw,rAnd tw,sThe difference is sent to a self-adaptive PID fuzzy controller, and the frequency of the chilled water pump is adjusted according to the output value;
s104, determining the supply and return water temperature t of the cooling waterv,rAnd tv,sThe difference is sent to a self-adaptive PID fuzzy controller, and the frequency of the cooling water pump is adjusted according to the output value;
s105, determining the outlet water temperature of the cooling tower and the outdoor wet bulb temperature tc,oAnd twbThe difference is determined in the sampling period, the deviation and the change rate of the difference from the set value are determined, the difference is sent to a self-adaptive PID fuzzy controller, and the frequency of a fan of the cooling tower is adjusted according to the output value;
s106, determining the total air supply amount P and setting the air supply amount P0Comparing, and adjusting the rotating speed of the fan according to the comparison result so as to adjust the total air supply quantity;
and S107, adjusting the opening of a fresh air valve and adjusting the fresh air ratio according to the requirements of different seasons on fresh air volume.
Compared with the prior art, the invention has the advantages that:
(1) the technical scheme of the invention adopts a self-adaptive fuzzy PID control mode, thereby avoiding the control instability of the central air-conditioning system caused by the characteristics of nonlinearity, large hysteresis, large inertia, time-varying property, strong coupling and the like;
(2) the self-adaptive energy-saving control method of the central air-conditioning system provided by the invention provides a full-flow control strategy of the central air-conditioning system, uniformly considers each component and link of the central air-conditioning system, and simultaneously adds an air treatment system control strategy comprising an air supply quantity control strategy and a fresh air quantity control strategy, so that the central air-conditioning system can run more energy-saving.
The invention is further described with reference to the following detailed description and accompanying drawings.
Drawings
FIG. 1 is a flow chart of the steps of the adaptive energy-saving control method of the central air-conditioning system according to the present invention.
FIG. 2 is a schematic diagram of an adaptive fuzzy PID control process according to the invention;
FIG. 3 is a schematic diagram of the adaptive fuzzy PID control system of the present invention.
Detailed Description
A self-adaptive energy-saving control method for a central air-conditioning system comprises the following steps:
s101, acquiring initial values of a chilled water end, a cooling water end and a fan end of a central air conditioner;
s102, monitoring and calculating the total cooling capacity Q of the air conditioning system in real time, and adjusting the number of air conditioning units according to the value of the total cooling capacity Q, wherein the method specifically comprises the following steps:
monitoring the total cooling capacity Q of the air conditioning system in real time and comparing the total cooling capacity Q with a design load threshold value Q0By contrast, if Q ═ Q (0.1 to 0.3) Q0Starting 1 unit; if Q is (0.3 to 0.6) Q0Loading one unit, starting n + 1-2 units, and changing into two units to run jointly; if Q is (0.6 to 1) Q0Starting 3 units with n +2, changing three units to synchronously operate, and enabling the loads among the units to be evenly distributed when a plurality of water chilling units with the same rated refrigerating capacity jointly operate;
the total cooling capacity of the air conditioning system can be calculated by detecting the flow m of the chilled water main pipe and the temperature difference of the supplied return water:
Q=Cm(tw,r-tw,s);
wherein C is the specific heat capacity of water, m is the total flow rate of chilled water, tw,rAnd tw,sThe supply water temperature and the return water temperature of the chilled water are respectively.
The unloading logic is contrary to the unloading logic, and corresponding adding and subtracting delay time needs to be met when the adding and subtracting operation of the water chilling unit is executed.
S103, determining the supply and return water temperature t of the chilled waterw,rAnd tw,sAnd the difference is sent to a self-adaptive PID fuzzy controller, and the frequency of the chilled water pump is regulated according to the output value, specifically:
chilled water supply and return water temperature difference delta t of header pipe of water separator and water collector is detected through temperature sensorw=tw,r-tw,sSending the difference value to a self-adaptive fuzzy PID controller to carry out fuzzy reasoning and fuzzy operation, outputting the frequency of the chilled water pump, and adjusting the rotating speed of the water pump, thereby realizingThe controller detects and adjusts the operation parameters in real time at present, so that the chilled water flow is matched with the air conditioner load, and the energy consumption of the water pump is greatly reduced;
the adaptive fuzzy PID control principle is based on constraint conditions:
Figure BDA0003465224910000031
calculating the flow rate of the chilled water by the change in the temperature difference, wherein Q is Cm (t)w,r-tw,s) And C is the specific heat capacity of water.
S104, determining the supply and return water temperature t of the cooling waterv,rAnd tv,sAnd the difference is sent to a self-adaptive PID fuzzy controller, and the frequency of the cooling water pump is adjusted according to the output value, specifically:
detecting the outlet water temperature difference delta t of the cooling water main pipe through a temperature sensorcThe motor frequency of the cooling water pump is adjusted according to the temperature through the self-adaptive fuzzy PID controller, so that the outlet water temperature of the cooling water main pipe is restored to a set value again, and the variable flow operation of the cooling water circulating system is realized;
the adaptive fuzzy PID control principle is based on constraint conditions:
Figure BDA0003465224910000032
the PWR is the compressor power, and the flow of the chilled water is calculated through temperature difference change.
S105, determining the outlet water temperature of the cooling tower and the outdoor wet bulb temperature tc,oAnd twbAnd the difference is determined in the sampling period, the deviation and the change rate of the difference from the set value are determined, the difference is sent to a self-adaptive PID fuzzy controller, and the frequency of the cooling tower fan is adjusted according to the output value, specifically:
according to the difference value delta t between the outlet water temperature of the cooling tower and the outdoor wet bulb temperatureo=tc,o-twbControlling the rotating speed of the cooling tower fans, and adjusting the frequency of each cooling tower fan according to the temperature through a self-adaptive fuzzy PID controller;
the adaptive fuzzy PID control principle is based on constraint conditions:
Figure BDA0003465224910000033
wherein mw represents the cooling tower fan air quantity, maIndicating cooling water flow rate, QrejIndicating the cooling tower heat rejection.
Wherein, the adaptive PID fuzzy controller in said steps S102, S103 and 104 has the corresponding variation e and the corresponding variation rate ec, KeAnd KecThe quantization factors respectively representing the deviation and the deviation change rate are output as parameter adjustment values delta Kp,ΔKi,ΔKd
Determining a basic theory domain and a fuzzy theory domain of an input variable and an output variable through measured data, selecting a fuzzy subset to describe the input variable and the output variable, establishing a fuzzy rule control table, and establishing a fuzzy reasoning and operation rule, wherein the fuzzy operation method adopts a Mamdani reasoning method.
The fuzzy implication of the control rule adopts a minimum value method, the fuzzy synthesis adopts a maximum value method, the final conclusion is obtained by comprehensive reasoning, and the defuzzification method adopts a maximum membership degree method. And multiplying the value obtained by fuzzy inference and deblurring by a scaling factor to obtain the adjusting value of the PID parameter.
S106, determining the total air supply amount P and setting the air supply amount P0The contrast is according to the comparison result regulation fan rotational speed to adjust total air supply volume, specifically do:
functional relation between total air quantity of system and rotating speed of fan
Figure BDA0003465224910000041
Functional relation between total air quantity of system and rotating speed of fan
Figure BDA0003465224910000042
Wherein W represents fan power; r and S are respectively the radius and the area of the fan impeller; eta is the fan efficiency;
the rotating speed of the blower is obtained according to the real-time air volume of the system, and the total air volume P and the set air volume P are used0And comparing and adjusting the rotating speed of the fan.
And S107, adjusting the opening of a fresh air valve according to the requirements of different seasons on fresh air volume, and adjusting the fresh air ratio.
The fresh air volume control adopts a minimum fresh air valve setting method, and respective minimum fresh air valve positions are respectively set when the variable air volume air conditioning system reaches the maximum total air supply volume and the minimum total air supply volume. When the system operates between the maximum air supply quantity and the minimum air supply quantity, the opening degree of the fresh air valve can be changed proportionally according to the change of the air supply quantity. In the transition season, the opening degree of the fresh air valve can be increased, the fresh air ratio is increased, and the purpose of energy-saving operation is achieved by using the cold energy of the fresh air.
The self-adaptive energy-saving control system of the central air-conditioning system is characterized by comprising the following modules:
air conditioning unit number adjusting module: the number of the air conditioning units is adjusted according to the value of the total cooling capacity Q;
the chilled water pump frequency adjusting module: for determining the temperature t of the supply and return water of the chilled waterw,rAnd tw,sAdjusting the frequency of the chilled water pump by using a self-adaptive PID fuzzy controller;
cooling water pump frequency regulation module: for determining the temperature t of cooling water supply and return waterv,rAnd tv,sThe difference is sent, and the frequency of the cooling water pump is adjusted by using a self-adaptive PID fuzzy controller;
cooling tower fan frequency adjustment module: for determining the outlet water temperature and the outdoor wet bulb temperature t of the cooling towerc,oAnd twbAdjusting the fan frequency of the cooling tower by using a self-adaptive PID fuzzy controller;
fan rotational speed regulation module: for providing a total air supply amount P and a set air supply amount P0Adjusting the rotating speed of the fan so as to adjust the total air supply quantity;
fresh air control module: the fresh air ratio is adjusted according to the requirements of different seasons on the fresh air volume.
A computer device comprising a memory, a processor and a computer program stored on the memory and executable on the processor, the processor implementing the following steps when executing the computer program:
s101, acquiring initial values of a chilled water end, a cooling water end and a fan end of a central air conditioner;
s102, monitoring and calculating the total cooling capacity Q of the air conditioning system in real time, and adjusting the number of air conditioning units according to the value of the total cooling capacity Q;
s103, determining the supply and return water temperature t of the chilled waterw,rAnd tw,sThe difference is sent to a self-adaptive PID fuzzy controller, and the frequency of the chilled water pump is adjusted according to the output value;
s104, determining the supply and return water temperature t of the cooling waterv,rAnd tv,sThe difference is sent to a self-adaptive PID fuzzy controller, and the frequency of the cooling water pump is adjusted according to the output value;
s105, determining the outlet water temperature of the cooling tower and the outdoor wet bulb temperature tc,oAnd twbThe difference is determined in the sampling period, the deviation and the change rate of the difference from the set value are determined, the difference is sent to a self-adaptive PID fuzzy controller, and the frequency of a fan of the cooling tower is adjusted according to the output value;
s106, determining the total air supply amount P and setting the air supply amount P0Comparing, and adjusting the rotating speed of the fan according to the comparison result so as to adjust the total air supply quantity;
and S107, adjusting the opening of a fresh air valve according to the requirements of different seasons on fresh air volume, and adjusting the fresh air ratio.
A computer-storable medium having stored thereon a computer program which, when executed by a processor, performs the steps of:
s101, acquiring initial values of a chilled water end, a cooling water end and a fan end of a central air conditioner;
s102, monitoring and calculating the total cooling capacity Q of the air conditioning system in real time, and adjusting the number of air conditioning units according to the value of the total cooling capacity Q;
s103, determining the supply and return water temperature t of the chilled waterw,rAnd tw,sThe difference is sent to a self-adaptive PID fuzzy controller, and the frequency of the chilled water pump is adjusted according to the output value;
s104, determining the supply and return water temperature t of the cooling waterv,rAnd tv,sThe difference is sent to a self-adaptive PID fuzzy controller, and the frequency of the cooling water pump is adjusted according to the output value;
s105, determining the temperature of the outlet water of the cooling towerDegree and outdoor wet bulb temperature tc,oAnd twbThe difference is determined in the sampling period, the deviation and the change rate of the difference from the set value are determined, the difference is sent to a self-adaptive PID fuzzy controller, and the frequency of a fan of the cooling tower is adjusted according to the output value;
s106, determining the total air supply amount P and setting the air supply amount P0Comparing, and adjusting the rotating speed of the fan according to the comparison result so as to adjust the total air supply quantity;
and S107, adjusting the opening of a fresh air valve and adjusting the fresh air ratio according to the requirements of different seasons on fresh air volume.
The invention is further described below with reference to the figures and examples.
Examples
Referring to fig. 1, a method for controlling adaptive energy saving of a central air conditioning system includes the following steps:
s101, acquiring initial values of a chilled water end, a cooling water end and a fan end of a central air conditioner;
s102, monitoring and calculating the total cooling capacity Q of the air conditioning system in real time, and adjusting the number of air conditioning units according to the value of the total cooling capacity Q, wherein the method specifically comprises the following steps:
monitoring the total cooling capacity Q of the air conditioning system in real time and comparing the total cooling capacity Q with a design load threshold value Q0By contrast, if Q ═ Q (0.1 to 0.3) Q0Starting 1 unit; if Q is (0.3-0.6) Q0Loading one unit, starting n + 1-2 units, and changing into two units to run jointly; if Q is (0.6 to 1) Q0Starting 3 units (n + 2), changing three units to synchronously operate, and enabling the loads among the units to be evenly distributed when a plurality of water chilling units with the same rated refrigerating capacity are jointly operated;
the total cooling capacity of the air conditioning system can be calculated by detecting the flow m of the chilled water main pipe and the temperature difference of the supplied return water:
Q=Cm(tw,r-tw,s);
wherein C is the specific heat capacity of water, m is the total flow rate of chilled water, tw,rAnd tw,sThe supply water temperature and the return water temperature of the chilled water are respectively.
The unloading logic is contrary to the unloading logic, and corresponding adding and subtracting delay time needs to be met when the adding and subtracting operation of the water chilling unit is executed.
S103, determining the supply and return water temperature t of the chilled waterw,rAnd tw,sAnd the difference is sent to a self-adaptive PID fuzzy controller, and the frequency of the chilled water pump is regulated according to the output value, specifically:
chilled water supply and return water temperature difference delta t of header pipe of water separator and water collector is detected through temperature sensorw=tw,r-tw,sThe difference value is sent to a self-adaptive fuzzy PID controller to carry out fuzzy reasoning and fuzzy operation, the frequency of the freezing water pump is output, and the rotating speed of the water pump is regulated, so that the regulation of the freezing water flow is realized, the controller carries out real-time detection and regulation on the operation parameters, the freezing water flow is matched with the air conditioner load, and the energy consumption of the water pump is greatly reduced;
the adaptive fuzzy PID control principle is based on constraint conditions:
Figure BDA0003465224910000061
calculating the flow rate of the chilled water by temperature difference change, wherein Q ═ Cm (t)w,r-tw,s) And C is the specific heat capacity of water.
S104, determining the supply and return water temperature t of the cooling waterv,rAnd tv,sAnd the difference is sent to a self-adaptive PID fuzzy controller, and the frequency of the cooling water pump is adjusted according to the output value, specifically:
detecting the outlet water temperature difference delta t of the cooling water main pipe through a temperature sensorcThe motor frequency of the cooling water pump is adjusted according to the temperature through the self-adaptive fuzzy PID controller, so that the outlet water temperature of the cooling water main pipe is restored to a set value again, and the variable flow operation of the cooling water circulating system is realized;
the adaptive fuzzy PID control principle is based on constraint conditions:
Figure BDA0003465224910000062
the PWR is the compressor power, and the flow of the chilled water is calculated through temperature difference change.
S105, determining the outlet water temperature of the cooling tower and the outdoor wet bulb temperature tc,oAnd twbDifference between them, and samplingDetermining the deviation and the change rate of the set value in the period, sending the deviation and the change rate into a self-adaptive PID fuzzy controller, and adjusting the fan frequency of the cooling tower according to the output value, wherein the method specifically comprises the following steps:
according to the difference value delta t between the outlet water temperature of the cooling tower and the outdoor wet bulb temperatureo=tc,o-twbControlling the rotating speed of the cooling tower fans, and adjusting the frequency of each cooling tower fan according to the temperature through a self-adaptive fuzzy PID controller;
the adaptive fuzzy PID control principle is based on constraint conditions:
Figure BDA0003465224910000063
wherein mw represents the cooling tower fan air quantity, maIndicating cooling water flow rate, QrejIndicating the cooling tower heat rejection.
Wherein, referring to fig. 2 and fig. 3, the adaptive PID fuzzy controller in steps S102, S103 and 104 has the corresponding variation e and the corresponding variation rate ec, KeAnd KecThe quantization factors respectively representing the deviation and the deviation change rate are output as parameter adjustment values delta Kp,ΔKi,ΔKd
Determining a basic theory domain and a fuzzy theory domain of an input variable and an output variable through measured data, selecting a fuzzy subset to describe the input variable and the output variable, establishing a fuzzy rule control table, and establishing a fuzzy reasoning and operation rule, wherein the fuzzy operation method adopts a Mamdani reasoning method.
The fuzzy implication of the control rule adopts a minimum value method, the fuzzy synthesis adopts a maximum value method, the final conclusion is obtained by comprehensive reasoning, and the defuzzification method adopts a maximum membership degree method. And multiplying the value obtained by fuzzy inference and deblurring by a scaling factor to obtain the adjusting value of the PID parameter.
The self-adaptive fuzzy PID controller completes self-adjustment of PID control variables by carrying out fuzzy reasoning and fuzzy operation on the real-time temperature of the room, thereby obtaining an output quantity UtThe air supply amount of the system is controlled by (the frequency of the blower of the air conditioning box), so that the room temperature is always kept at the set value.
The self-adaptive fuzzy PID controller has the advantages of a fuzzy controller and a PID controller, and can perform fuzzy reasoning and fuzzy operation on the real-time input of a system, so that the online dynamic self-tuning of PID control parameters is realized.
The Simulink simulation result shows that the conventional PID control system has slight oscillation, the adjusting time is 400s and is longer than the time of the self-adaptive fuzzy PID control (300s), and the self-adaptive fuzzy PID control is quick and stable in adjustment, free of overshoot and free of oscillation.
S106, determining the total air supply amount P and setting the air supply amount P0The contrast is according to the comparison result regulation fan rotational speed to adjust total air supply volume, specifically do:
functional relation between total air quantity of system and rotating speed of fan
Figure BDA0003465224910000071
Wherein W represents fan power; r and S are respectively the radius and the area of the fan impeller; eta is the fan efficiency;
namely the air quantity and the rotating speed of the fan are in linear proportional relation;
calculating the rotation speed of the blower according to the real-time air volume of the system, and calculating the total air volume P and the set air volume P0And comparing and adjusting the rotating speed of the fan.
And S107, adjusting the opening of a fresh air valve according to the requirements of different seasons on fresh air volume, and adjusting the fresh air ratio.
The fresh air volume control adopts a minimum fresh air valve setting method, and respective minimum fresh air valve positions are respectively set when the variable air volume air conditioning system reaches the maximum total air supply volume and the minimum total air supply volume. When the system operates between the maximum air supply quantity and the minimum air supply quantity, the opening degree of the fresh air valve can be changed proportionally according to the change of the air supply quantity. In the transition season, the opening degree of the fresh air valve can be increased, the fresh air ratio is increased, and the purpose of energy-saving operation is achieved by utilizing the cold energy of the fresh air.
The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention, and various modifications and changes may be made by those skilled in the art. Any modification, equivalent replacement, or improvement made within the spirit and principle of the present invention shall fall within the protection scope of the present invention.

Claims (10)

1. A self-adaptive energy-saving control method of a central air-conditioning system is characterized by comprising the following steps:
s101, acquiring initial values of a chilled water end, a cooling water end and a fan end of a central air conditioner;
s102, monitoring and calculating the total cooling capacity Q of the air conditioning system in real time, and adjusting the number of air conditioning units according to the value of the total cooling capacity Q;
s103, determining the supply and return water temperature t of the chilled waterw,rAnd tw,sThe difference is sent to a self-adaptive PID fuzzy controller, and the frequency of the chilled water pump is adjusted according to the output value;
s104, determining the supply and return water temperature t of the cooling waterv,rAnd tv,sThe difference is sent to a self-adaptive PID fuzzy controller, and the frequency of the cooling water pump is adjusted according to the output value;
s105, determining the outlet water temperature of the cooling tower and the outdoor wet bulb temperature tc,oAnd twbThe difference is determined in the sampling period, the deviation and the change rate of the difference from the set value are determined, the difference is sent to a self-adaptive PID fuzzy controller, and the frequency of a fan of the cooling tower is adjusted according to the output value;
s106, determining the total air supply amount P and setting the air supply amount P0Comparing, and adjusting the rotating speed of the fan according to the comparison result so as to adjust the total air supply quantity;
and S107, adjusting the opening of a fresh air valve and adjusting the fresh air ratio according to the requirements of different seasons on fresh air volume.
2. The adaptive energy-saving control method of the central air-conditioning system according to claim 1, wherein the number of the air-conditioning units is adjusted according to the value of the total cooling capacity Q in step S102, specifically:
monitoring the total cooling capacity Q of the air conditioning system in real time and comparing the total cooling capacity Q with a design load threshold value Q0By contrast, if Q ═ Q (0.1 to 0.3) Q0Starting n sets of units; if Q is (0.3 to 0.6) Q0Starting n +1 machine sets; if Q is (0.6-1) Q0Starting n +2 machine sets;
the total cooling capacity Q of the air conditioning system is equal to Cm (t)w,r-tw,s);
Wherein C is the specific heat capacity of water, m is the total flow rate of chilled water, tw,rAnd tw,sThe supply water temperature and the return water temperature of the chilled water are respectively.
3. The adaptive energy-saving control method for central air-conditioning system according to claim 1, wherein the adaptive PID fuzzy controllers in S102, S103 and S104 have the input of the corresponding variation e and the variation rate ec and the output of the adaptive PID fuzzy controllers is the parameter adjustment value Δ Kp,ΔKi,ΔKd
And determining a basic discourse domain and a fuzzy discourse domain of the input and output variables, selecting a fuzzy subset to describe the input variables and the output variables, and establishing a fuzzy rule control table.
4. The adaptive energy-saving control method for the central air-conditioning system according to claim 3, wherein the adjusting the frequency of the chilled water pump according to the output value in step S103 is specifically as follows:
detecting chilled water supply and return water temperature difference delta t of header pipe of water separator and water collectorw=tw,r-tw,sSending the difference value to a self-adaptive fuzzy PID controller for fuzzy reasoning and fuzzy operation, outputting the frequency of the freezing water pump, and adjusting the rotating speed of the water pump, thereby realizing the adjustment of the flow of the freezing water;
the adaptive fuzzy PID control principle is based on constraint conditions:
Figure FDA0003465224900000021
calculating the flow rate of the chilled water by temperature difference change, wherein Q ═ Cm (t)w,r-tw,s) And C is the specific heat capacity of water.
5. The adaptive energy-saving control method for the central air-conditioning system according to claim 3, wherein the adjusting the frequency of the cooling water pump according to the output value in the step S104 specifically comprises:
detecting the outlet water temperature difference delta t of the cooling water main pipecThe motor frequency of the cooling water pump is adjusted according to the temperature through the self-adaptive fuzzy PID controller, so that the outlet water temperature of the cooling water main pipe is restored to a set value again, and the variable flow operation of the cooling water circulating system is realized;
the adaptive fuzzy PID control principle is based on constraint conditions:
Figure FDA0003465224900000022
the PWR is the compressor power, and the flow of the chilled water is calculated through temperature difference change.
6. The adaptive energy-saving control method for the central air-conditioning system according to claim 3, wherein the adjusting the fan frequency of the cooling tower according to the output value in the step S105 specifically comprises:
according to the difference value delta t between the outlet water temperature of the cooling tower and the outdoor wet bulb temperatureo=tc,o-twbControlling the rotating speed of the cooling tower fans, and adjusting the frequency of each cooling tower fan according to the temperature through a self-adaptive fuzzy PID controller;
the adaptive fuzzy PID control principle is based on constraint conditions:
Figure FDA0003465224900000023
wherein m iswShows the air quantity m of the cooling tower fanaIndicating cooling water flow rate, QrejIndicating the cooling tower heat rejection.
7. The adaptive energy-saving control method for the central air-conditioning system according to claim 1, wherein the adjusting of the total air supply amount in step S106 is specifically:
functional relation between total air quantity of system and rotating speed of fan
Figure FDA0003465224900000024
Wherein W represents fan power; r and S are respectively the radius and the area of the fan impeller; eta is the fan efficiency;
calculating the rotation speed of the blower according to the real-time air volume of the system, and calculating the total air volume P and the set air volume P0And comparing and adjusting the rotating speed of the fan.
8. The self-adaptive energy-saving control system of the central air-conditioning system is characterized by comprising the following modules:
air conditioning unit number adjusting module: the number of the air conditioning units is adjusted according to the value of the total cooling capacity Q;
the chilled water pump frequency adjusting module: for determining the temperature t of the supply and return water of the chilled waterw,rAnd tw,sAdjusting the frequency of the chilled water pump by using a self-adaptive PID fuzzy controller;
cooling water pump frequency regulation module: for determining the temperature t of cooling water supply and return waterv,rAnd tv,sThe difference is sent, and the frequency of the cooling water pump is adjusted by using a self-adaptive PID fuzzy controller;
cooling tower fan frequency adjustment module: for determining the outlet water temperature and the outdoor wet bulb temperature t of the cooling towerc,oAnd twbAdjusting the fan frequency of the cooling tower by using a self-adaptive PID fuzzy controller;
fan rotational speed regulation module: for providing a total air supply amount P and a set air supply amount P0Adjusting the rotating speed of the fan so as to adjust the total air supply quantity;
fresh air control module: the fresh air ratio is adjusted according to the requirements of different seasons on the fresh air volume.
9. A computer arrangement comprising a memory, a processor and a computer program stored on the memory and executable on the processor, characterized in that the steps of the method according to any of claims 1-7 are implemented by the processor when executing the computer program.
10. A computer-storable medium having a computer program stored thereon, wherein the computer program is adapted to carry out the steps of the method according to any one of claims 1-7 when executed by a processor.
CN202210027528.2A 2022-01-11 2022-01-11 Self-adaptive energy-saving control method for central air-conditioning system Pending CN114440409A (en)

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