Characteristics Research And Modeling Of Valve Positioner

Regulating valve is the very important and indispensable terminal regulatory element in automation industry and valve positioner is its main supporting component,which is matched up with actuator so as to ensure the right place of regulating valve.This paper firstly introduced the structural and working principle of electricity-gas valve positioner and deeply investigated the working process of its main components respectively.Torque motor's model was constructed based on the electromagnetism knowledge,and the nozzle flapper valve's model was established from the point of flow balance,its fluid field was analysed by using ANSYS Workbench CEX,relay's model was established from the view of dynamic balance.This paper deduced the model of valve locator system combined with the model of pneumatic actuator and regulating valve.It is the first-order system model.Considering of the existence of gas compressibility(z).mechanism friction(f)and the element elastic reaction(k)in actual industrial process,the valve locator system's model is expressed as the first-order inertia plus pure lag model.Because of the individual performance parameter of the model is difficult to obtain,this paper verified its correctness via the ident toolbox of MATLAB based on the experimental data collected at the production scene.Furthermore,we used fuzzy intelligent weight function together with bang-bang control rules and the PID control method to control the valve locator system respectively in order to improve the system response characteristic.