Research On Modeling And Control Method Of Pneumatic Control Valve

Pneumatic control valve is the important component in automation process industry, and its control performance is the key to the research content. A model which can accurately reflect the characteristics of pneumatic control valve is the basis of the research of pneumatic control valve system control. Pneumatic control valve is essentially a nonlinear system, and the research of its nonlinear characteristics can help us to improve and perfect the model. Quantified evaluation and analysis of the control performance of the pneumatic control valve’s control algorithm which based on the model simulation and experimental studies is important to get the control parameters which can have fast, accurate and stable control performance. It has positive meanings to save costs of production and to improve production efficiency.The contents of this dissertation are as follows:Firstly, the dissertation introduced the structure and working principle of pneumatic control valve system. The system is divided into three subsystems, including the smart positioner, pneumatic actuator, control valve. Thanks to the idea of mathematical modeling, the mechanism model, which was given by this dissertation, has good portability and scalability.Secondly, the dissertation carried out the simulation of no load control valve model. The simulation proved that the model can reflect the characteristics of the pneumatic control valve accurately. By analyzing the data of a series of pneumatic control valve open loop experiment, we identified the four nonlinear characteristic of pneumatic regulating valve system which provide reference for the future perfection and improvement of the model.Thirdly, the dissertation studies on pneumatic control algorithm of control valve. A method for parameter identification model based on the step response of the system is given. The dissertation gives the tuning method of IMC-PID pneumatic valve positioner control algorithm, discussed on how to select the optimal adjustable parameters in the tuning formula.Finally, the dissertation introduces the construction and experiment of open loop and close loop experiment platform. By conducting comparison experiments on the performance of aerodynamic value control, we found that using the MC-PID control parameter tuning algorithm of the pneumatic valve control system is more accurate, fast and stable.This dissertation is based on huge amount of reading and theoretical analysis, and the length of experiments in the lab and factory is near to 1000 hours.