Research And Application Of Control Technology For High Precision Valve Positioner

In industrial applications,the demand for flow control is higher and higher.Correspondingly,it also puts forward higher requirements for the performance of intelligent valve positioners.As the control object of the intelligent electric pneumatic valve positioner,the pneumatic actuator has the characteristics of nonlinear,time-varying and lag,and it should be used in the multi disturbance environment of industry,which makes it difficult to achieve higher performance requirements by using the traditional control algorithm.In order to improve the control performance of the valve locator,this paper,based on the theory of intelligent control,studies the control technology of the valve locator in a certain enterprise as the application background,studies the control technology of the valve locator,aiming at the characteristics of the nonlinear,time-varying and lagging characteristics of the pneumatic actuator.The main work of this article is as follows:(1)In-depth understanding of the working principle of valve positioner,a lot of research has been done on the characteristics of the control object of valve positioner,and the conclusion that pneumatic actuator is a non-linear,time-varying and hysteretic control object has been drawn.(2)A relay feedback identification algorithm is designed.The characteristic parameters of the valve positioning system are calculated by the periodic oscillation waveform of the system.By comparing the simulation results with the experimental results,the approximation of the model identified by relay feedback is verified.(3)Research on control strategy of valve positioner.Because the pneumatic control system is a time-varying non-linear control system,it is difficult to obtain better control effect by using fixed parameter PID controller.In this paper,a fuzzy adaptive PID controller with Smith predictor is designed,which combines the self-adaptive characteristic of the fuzzy controller with the high contro l precision of the PID controller.The feasibility of the controller is analyzed by simulation experiments based on Simulink model.(4)In order to further test and verify the fuzzy adaptive PID control algorithm,this paper constructs an experimental platform of high-precision valve positioner control technology.By writing programs,debugging hardware and software online repeatedly,and analyzing and comparing experimental data with simulation data,the fuzzy adaptive PID control algorithm is optimized,which further enhances the practicability of the algorithm.Finally,a number of experimental data show that the control accuracy of valve positioner has been improved to 0.3%,which meets the expected requirements.