Temperature and humidity cascade control method based on AHU return air unit

Abstract

The invention relates to a temperature and humidity cascade control method based on an AHU return air unit. The method comprises the following steps: (1) calculating a temperature and humidity average value of a biosafety laboratory room as an actual temperature and humidity reference value; (2) determining a required temperature target value and a required humidity target value; (3) establishing a temperature and humidity cascade control mathematical model of the AHU return air unit, inputting parameters as measured values and set values of return air temperature and humidity and supply air temperature and humidity, and controlling outputs as the opening degree of a hot water valve, the opening degree of a cold water valve and the opening degree of a humidification valve. The method has the advantages that the dynamic characteristic of actual control is improved, the adaptability to load change is improved, and the system control quality is improved; the temperature and humidity fluctuation of a controlled room is responded in advance, the response speed of a system is increased, the adjusting quality of the system is improved, the cascade control precision is higher, and the stability is higher; and the simultaneous opening time of the valves is reduced, energy conservation and consumption reduction are realized to a certain extent, and system control is efficient and energy-saving.

Description

technical field [0001] The invention relates to a temperature and humidity cascade control method based on an AHU return air unit, in particular to a temperature and humidity cascade control method based on an AHU return air unit applied to a biological safety laboratory construction project, and belongs to the technical field of automatic control. Background technique [0002] In the biosafety laboratory experiment and production process, it is necessary to maintain the dynamic balance of various indicators such as pressure gradient, temperature and humidity in each area of ​​the laboratory to ensure the protection of biosafety. Among them, the temperature and humidity control is mainly based on the PID control of the surface cooling section, heating section and humidification section of the AHU air-conditioning unit to complete the dehumidification (or humidification) and cooling (or heating) of the humid air, etc. Wind, so as to achieve the purpose of controlling the temp...

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Problems solved by technology

[0004] In the complex and changeable production environment of the biosafety laboratory, the above-mentioned control scheme in the prior art can meet the requirements in most cases due to the severe coupling of temperature and humidity. Poor performance and waste of cold and heat sources, low control precision, high control cost and other defects

[0005] Specifically, the temperature and humidity control process has great nonlinearity, hysteresis, and time-varying properties. However, the above-mentioned control technology in the prior art mainly adopts a single-loop control method for temperature and humidity. The response speed of temperature and humidity adjustment is slow, and it is greatly affected by environmental interference, resulting in large fluctuations in temperature and humidity in the laboratory room, and poor temperature and humidity control stability; at the same time, the above-mentioned control technology adopts a single-valve single-control mode. The opening of the hot water valve is used to adjust the flow of cold water or hot water. When the load changes frequently, the hot and cold control valves are opened at the same time, and the opening will be opened repeatedly, which will cause a lot of unnecessary waste during long-term system operation. The consumption of cooling or heat is wasted, resulting in high control costs of air conditioning units

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