Research on control algorithm of intelligent valve positioner based on parameter self-tuning

Pneumatic valve positioner is widely used in chemical industry, energy, oil and gas, water treatment, paper industry and other industrial fields. The type of foreign valve positioner has been transferred from mechanical and electronic to intelligent electronic. However, the domestic research on valve positioner research started late, the technology is relatively backward, the failure rate is high. The main reason that affects the performance of domestic valve positioners is due to the immature control algorithm. Based on the analysis of the traditional five-step switch control algorithm, an improved control algorithm and a new parameter auto-tuning method are proposed. All control parameters in the improved control algorithm are obtained by self-tuning, which improves the universality of the algorithm. The parameter self-tuning method can automatically identify the stroke type, end position, maximum overshoot, optimal PWM duty ratio of different valve positions and other parameters, which provides the basis for the control parameter selection of the improved control algorithm. The control algorithm was implemented and verified with the help of an experimental bench. The experimental results show that the improved control algorithm not only greatly reduces the valve position adjustment time, but also avoids the overshoot phenomenon in the whole stroke range.