Research On Control Algorithm Of Intelligent Electric Valve Positioner

In the industrial automation production process,the regulating valve is the end of the process control system execution parts.Specially,the pneumatic valve has a share of about 70%.its performance directly affects the safety and stability of the process.The valve positioner,which is the core of the control valve accessories,greatly improve the regulator static characteristic and dynamic characteristic,increase the flexibility of the control,has become the "brain" of the regulating valve control system.Intelligent electric valve positioner has incomparably advantage which the traditional valve positioner.It has become a development trend and research emphasis,but domestic research and development at the core of the positioning control algorithm has large room for improvement in dynamic and static performance.Belongs to application research,aiming at intelligent electric valve positioner,including pneumatic amplifier,I/P conversion unit and PID controller,the parameter tuning of double closed loop system based on neural network PID algorithm and based on gas chamber pressure switch control PID algorithm are proposed.Due to various interference factors in the control valve control system,it tend to affect the positioning control performance.in view of the regulating valve control system stability,the analysis of the effect interference factors affect the stability performance,and proposes the corresponding solution.In this paper,two kinds of control algorithm parameters are set up conveniently,and the effectiveness of the control performance and the applicability of different specification control valves are verified through simulation research and a large number of physical valve experiments.First,the pneumatic positioning system has been established in laboratory experiment platform,based on the plenty of physical valve experimental research,found interference factors that influence the stability of the regulating valve control system,including the air pressure,the viscous,the unbalanced force of valve core,this paper puts forward the method of feedforward controller to compensate the effect on the stability of the air supply,and the Knocker algorithm is used to eliminate or reduce the stability of the viscous effects.Secondly,the double closed-loop control system is constructed by introducing the gas chamber pressure,and the parameter tuning of double closed loop system based on neural network PID algorithm is proposed.The algorithm adopts correlation analysis reflect the valve features are extracted as the main parameters of the neural network input layer,the optimal PID parameters of the neural network sample set are acquired for by the form of IMC tuning and manual trimming.Finally,focusing on the rapidity of the positioning control valve system,a switch control PID algorithm based on gas chamber pressure is proposed.The algorithm uses a hard switch to output control signals and designs three sub-controllers to switch control.In laboratory has been set up the regulator test platform and the enterprise production site,the parameter tuning of double closed loop system based on neural network PID algorithm and switch control PID algorithm based on the gas chamber pressure are tested,compared with SVP300 series intelligent valve positioner closed-loop experiments,to verify the effectiveness,diversity,and applicability of the two algorithms.