Research On The Design And Performance Assessment Of PID Controller In Industrial Processes

PID control is the most common control method used in industrial process control, mainly because, despite their simplicity, they can assure satisfactory performances for a wide range of processes. This thesis describes the three important methods for designing PID controller: IMC-based method, frequency method and direct synthesis method. We respectively design the PID controllers for the first-order plus dead-time processes, second-order plus dead-time processes, non-minimum phase processes, integrating and unstable processes, then, performance assessment and robustness metrics are used to compare the PID controllers of the individual process. Simulation results have shown that there are obvious differences in both PID controller parameters and control loop performance for each process, and it is impossible to use same PID controller parameters for optimizing total controller performance indices at one time. Based on these facts, the stochastic, deterministic and integrated performance measures are utilized to solve optimal PID controller parameters, for providing a new design approach of PID controller. The main research works are as follows:1. Chapter 1 reviews the state-of-the-art in PID controller, represents the three methods for designing PID controller: IMC-based method, frequency method and direct synthesis method, and introduces some control performance measures. Moreover, a short survey of controller performance assessment and monitoring technique is given.2. In chapter 2 and chapter 3, we respectively design PID controller using the three methods for stable processes, integrating and unstable processes. The PID controller performances of the individual process are compared with both deterministic performance and robustness. Some valuable experiences for choosing reasonable design method are given from the integrative comparison.3. Chapter 4 adopts the deterministic performance measures and stochastic performance measures of PID controller to find optimal tuning parameters, considering robustness of the controller. Simulation and computation results have shown that the optimal PID controller provides good control performance in terms ofstochastic disturbance rejection, set-point tracking, and strong robustness.4. The main contributions of this thesis are summarized in chapter 5, along with directions for future work.