Temperature Control of a CSTR Using a Nonlinear PID Controller

Abstract

Continuous stirred tank reactor (CSTR) which plays a key role in the chemical plants exhibits highly nonlinear behavior as well as time-varying characteristics during operation. So, CSTR process control over the whole operating range has been a challenging issue especially for control engineers. A variety of feedback control algorithms and their tuning methods have been developed to guarantee the satisfactory performance despite the varied dynamic characteristics of CSTRs.

This thesis presents a scheme of designing a nonlinear PID controller incorporating with a real-coded genetic algorithm (RCGA) for the temperature control of a CSTR process. The gains of the NPID controller are composed of easily implementable nonlinear functions based on the error and/or the error rate and its parameters are tuned using the RCGA by minimizing the integral of time-weighted absolute error (ITAE).

A set of simulation works for reference tracking and disturbance rejecting performances and robustness to parameter changes are carried out to compare with two other nonlinear controllers and show the feasibility of the proposed method.