In the management and control process of HVAC systems, the effective application of automated air conditioning control systems plays an important role in reducing energy consumption, improving system operation quality, and strengthening labor intensity management and control. Next, follow us to learn about the application of automatic control technology in central air-conditioning systems!
At this stage, in the management and control process of HVAC control systems, the effective application of automated central air-conditioning control systems has played an important role in reducing energy consumption, improving system operation quality, and strengthening labor intensity management and control. important role. This article mainly briefly describes the application of the automatic control system of the central air-conditioning control system. The article first introduces the automatic control technology in the central air-conditioning system, and then analyzes the application of intelligent control technology, hoping to be able to provide relevant information in the later period. Work is guided.
At present, with the continuous development of science and technology, central air conditioning control systems are increasingly used in the indoor temperature regulation process of some large buildings such as high-end office buildings and factory buildings. At the same time, due to the continuous maturity of automation and intelligent control technology, automatic control technology has gradually been introduced into the central air conditioning control and adjustment system, which not only provides people with a more comfortable working and living environment, but also saves money. It also plays a huge role in operating costs and extending the service life of the central air conditioning control system.
1 Automatic control technology in the central air-conditioning control system
1.1 Adjustment of cold and heat sources and water pipe systems
For the host system of the central air-conditioning control system , its own unit controller can provide multiple indicators such as the inlet and outlet temperatures of condensers and evaporators and other equipment, as well as the pressure of the water flow switch compressor. In this process, the system mainly adopts a group control mode, which effectively realizes the automatic management and control of the heat pump, and also exerts a good monitoring, query and alarm functions.
Once a fault occurs during the normal operation of the unit, the system main controller will immediately display the corresponding display and issue an alarm; in addition, it can also adjust and modify the relevant values ??set by the system_ Wait for operations. For example, at different times of the day, such as night and day, there are large differences in the values ??set by the system. Operate the system compressor in conjunction with relevant commands, and adjust the compressor inlet guide vane valve with reference to the set value at the outlet of the refrigeration machine room. In this process, the outgoing temperature of the chilled water can also be set, and the operating status of the host can be monitored in real time through water flow sensors and temperature sensors.
1.2 Parameter measurement of fresh air and air conditioning units
In order to better improve the cleanliness and freshness of indoor air and indoor comfort, the central air conditioning control system needs to be able to measure the fresh air in a timely manner. Replenish. Under normal circumstances, temperature and humidity sensors need to be installed at the position of the air supply channel of the fresh air air conditioning unit, and the flow rate can be effectively controlled through the application of humidification, thereby better meeting the design requirements. The central air-conditioning system can also complete the automatic replacement of the windshield based on the indoor temperature and moderate computing load, thereby successfully achieving effective control of the air supply volume. In addition, the central air-conditioning control system can also adjust the opening of the air valve based on the indoor and outdoor temperature and humidity as well as the system's predetermined temperature and humidity, and implement a linkage control on the exhaust valve, thus achieving an effect of reducing consumption and saving energy.
The fresh air valve and exhaust valve will be in a closed state after the unit stops running. At this time, the return air valve should remain fully open. The automatic management and control of the central air conditioning system can be realized by using the DOC controller. . In practice, the water valve is adjusted through PID based on the fresh air temperature, thereby effectively ensuring that the air supply degree is at the predetermined value. At the same time, by controlling the steam valve and humidification valve, the air temperature at the outlet of the fan in winter is guaranteed to meet the standard. Moreover, the system can also monitor the temperature and humidity at the fan outlet and the pressure difference on both sides of the fresh air filter in real time. Once these values ??are abnormal, the system will automatically alarm.
1.3 Monitoring of fan coil units in the central air conditioning system
The heating and cooling equipment in the central air conditioning system mainly consists of air conditioning units, fresh air units and a large number of fan coil units. Among them, fan coil units are currently mainly of two types on the market: DOC controllers and controllers with communication capabilities; among them, the DOC controller has the communication function with the system host and can control the chiller and cold water well. This type The control market price is generally higher; as for coil controllers with communication capabilities, it is recommended to group the fan coil units according to the connection conditions of the water system during the application process, and install flow meters and Installation of water temperature sensor and water pressure transmitter.
At present, in the automatic control process of the central air-conditioning control system, it is not possible to completely rely on DOC technology for control, so it is impossible to apply various types of air in the system's cooling effect control and air volume debugging. The automatic adjustment function of the valve is used to achieve the design requirements of uniform air volume. To solve this kind of problem, the most commonly used method is the "base air outlet method", which means to adjust the air volume manually.
2 Application of intelligent control technology
Take a hotel as an example. A total of 3 cooling water pumps are installed in this hotel, with motor capacity and load rate of 65KW and 90 respectively. In this central air conditioning system, the lower computer is S7-300PLC and the upper computer is the monitoring software. The energy saving of the central air conditioning inverter is shown in the figure.
The central air-conditioning control technology in this case mainly applies two major intelligent control technologies: fuzzy control technology and neural network control technology; among which fuzzy control technology realizes some problems that cannot be modeled by simulating human thinking. Effective control; in addition, based on the application of variable radio frequency technology and PLC, the application of fuzzy controller can achieve a more significant effect than the traditional PID control mode.
2.1 Application of automatic control system in constant air volume air conditioning system
During the operation of the constant air volume system, once the air volume is determined, the fan will maintain a full air volume regardless of how the load changes. operation, and as the supply air temperature changes, it will also well meet the changing needs of indoor cooling and heating loads, thereby better maintaining the indoor temperature and humidity in an optimal state. A general central control system must not only have basic heating, heating, and dehumidification functions, but also be able to intelligently control system exhaust vents, electric dampers, return air fans and other components to achieve cyclic automated operation of the control system. , which can also achieve a good control effect. In the automatic control system of the constant air volume air conditioning system, its focus is on the management and control of air conditioning temperature and humidity adjustment and application ratios of exhaust valves, fresh air valves, return air valves, etc.
2.2 Effective application of automatic control in variable air volume air conditioning systems
During the operation of the variable air volume system, when the indoor cooling and heating loads change, it will not cause air supply Changes in temperature only change the air volume, so the indoor temperature and humidity can be well maintained. The system has automatic control air valves arranged at the air supply inlets of each room. In its practical application process, through the control and adjustment of the air supply volume, good control of the temperature and humidity of each room is achieved. One of the main features of the variable air volume control system is that the supply air temperature remains constant, that is, the opening of the recovery regulating valve of the surface cooler remains unchanged.
In short, the effective application of automatic control systems in central air-conditioning has exerted great application value. It not only achieves a good energy saving and consumption reduction effect, but also improves the control efficiency of the system. A significant improvement. Therefore, the application prospects of automatic control systems in central air-conditioning systems are also very broad.
The above is a detailed answer about the application of automatic control technology in central air-conditioning systems. I wonder if everyone is satisfied with our introduction.