Research On Self-tuning Algorithm Of Intelligent Valve Positioner

Intelligent pneumatic valve positioner plays an important role in the field of industrial control, its high sensitivity、high reliability、simple operation and its bus control function can Improve the dynamic response and steady state performance of pneumatic valve。This thesis is a study of the intelligent electrical valve positioner, which was consisted of pneumatic actuator and nozzle flapper type I/P conversion unit。As key technical difficulties of the intelligent electrical valve positioner, the locate control algorithm and self-tuning algorithm research was crucial for the locator project development。System identification means to get the Mathematical model of the process, and in this area there are some mature theory which could refer to。The valve system identification needs to be combined with the specific physical characteristics of the valve and design a method with high performance、high precision。This thesis put forward a method which could extract the accurate first order plus time delay model form the relay feedback experiment on the pneumatic valvThe ordinary PID control algorithm is difficult to achieve the extremely high demand on dynamic control performance (fast, no overshoot)of the intelligent electrical valve positioner, so we use the segmented PID control。For the PID control parameters self tuning method, after simulation comparing for some current tuning method of PID control, we select the tuning method based on the minimum ISTE performance, which cares for both of the transition process deviation and its Adjustment time。 This thesis introduces in detail on how to use the ISTE rules in MATLAB to select the optimized PID control parameter, on the basis of the mathematical model。Because of the limited computing capability of the valve positioner, the whole process of the System identification and controller parameter optimization can’t operate on-line and real-time, so we use the combination of on-line identification and control parameter look-up table method to achieve the self-tuning function:Form a complete control parameter database by taking a lot of experiments, and use a streamlined method to identify specific characteristics of valve, then look up from the valve characteristic parameter table to obtain the corresponding control parameters。In the end this thesis introduces the self-tuning algorithm and control algorithm realization method, and gives the specific types of valves on the actual control effect, which showed that the method is correct and effective。...