A Study Of Fuzzy Immune PID Algorithm And Its Control Of Expansion Machine’s Temperature

In recent years, expansion machine is increasingly used in industrial production because of its high efficiency, simple, easy operation and less need of external conditions etc. The oil gas primary treatment system contains many kinds of key equipment and expansion machine is one of the more critical ones. Expansion machine is the main refrigeration equipment of natural gas cryogenic equipment and the production of light hydrocarbon and the quality of the products in the natural gas cryogenic equipment is directly related to the operation of expansion machine. Air works outside and expends its inner energy by the adiabatic expansion in the expansion machine. The main function of expansion machine is to reduce the pressure and temperature of the gas to achieve the purpose of refrigeration and cooling by that. So the temperature control of the expansion machine is of great importance.Conventional PID controller in temperature control system is not perfect and it may encounter many problems, such as large overshoot, long adjusting time and even poor stability in the control with time delay. The traditional PID controller has poor control effect for the complex system with no precise mathematical model. The uncertainty of parameters or load causes the control effect of traditional PID controller can not meet the requirements of high performance easily.1.Firstly, the Paper introduces conventional PID controller, fuzzy controller and immune feedback system in this article. And analyze the advantages and disadvantages of three kinds of control method in detail.2.We study the structure and design of fuzzy immune self-adaptive PID control method based on the analysis of the advantages and disadvantages of the PID control, fuzzy control method and immune feedback control method in this paper. This kind of controller has a simple structure. Its parameters are also convenient to be adjusted. Put conventional PID control algorithm, fuzzy PID control algorithm and fuzzy immune PID control algorithm to controlled object according to the characteristics of the expansion temperature control system.And then making a detailed analysis and designing the corresponding controller respectively.3.We regard the simplified model of the expansion machine as the controlled object and make a simulation of fuzzy immune PID control method in MATLAB. And comparing it with the result of conventional PID control method and fuzzy PID control method. The Matlab simulation results proved that the fuzzy-immune PID control is an effective arithmetic with the advantages of quick response, good robust, strong anti-interference performance and gooddynamic and static performance in control of outlet temperature. Using the method can achieve ideal control effect and it has certain reference value in the practical engineering application.