Developing And Researching PID Parameters Auto-tuning Software Package In Distributed Control System MAX1000+plus

Proportional-Integral-Derivative (PID) is one of the most widely used control strategies in the process control engineering practice. The best tuning parameters of PID has a crucial effect on control performance. The desired requirements on control system can be met as long as the PID parameters accommodated with the process dynamics are obtained. However, the artificial methods for tuning PID parameters are so far applied commonly regardless of in the domestic or overseas process control engineering practice, which cause the PID tuning job extremely time-consuming and can not assure of the best control system performances consequently, particularly for these time variant processes. Hence, the research on automatic tuning and adaptation technologies for PID control is on the agenda. Furthermore, the rapid development of control theory and the application of advanced control equipment DCS provide an opportunity for PID parameters tuning.This paper researches the developing of PID parameters auto-tuning software package on distributed control system MAX1000+plus's workstation, and adopts three strategies for tuning PID parameters in terms of the process characteristics, namely automatic tuning, gain scheduling and PID adaptive control. Then, two alternative schemes can be used to obtain the process dynamics. One is transient response method based on step test, the other is frequency response method based on relay feedback. The proposed PID parameters auto-tuning algorithm, which uses the idea of placement system's dominant poles for reference and regards the maximum sensitivity as one of performance criteria, is concluded from the analyses of several algorithms. Meanwhile, the auto-tuning strategies focused on cascade and feedforward control systems are put forward as well. On the foundation of above, PID parameters auto-tuning software package on MAX1000+plus's workstation is developed with Visual C++. Finally, the PID control simulation platform, which is composed of the process model established by MATLAB and model's connection with virtual DPU, is developed for this software.The simulation results show that this tuning algorithm that has taken the processes characteristics differences into consideration is correct, advanced and practical in engineering application and meets the requirements on the control system. The software adopted this auto-tuning algorithm is rationally designed; its human machine interface is friendly; its functionality is versatile; and its application scope is broad, not only for single-loop control system, but for cascade and feedforward control systems. The research work in this paper realized PID auto-tuning algorithm on MAX1000+plus's workstation and further developed DCS's function.