The IMC-PID controller design for TITO process using closed-loop identification method

A new auto-tuning method is presented in this paper for the TITO process with time delay. The first step is to identify the process model and the second step is to design the IMC-PID controller. In the identifying procedure, both the bias relay test and the idea relay test are involved to identify the model. The important feature of the proposed method is that it does not require the prior information about the process and the steady-state process gain can be directly obtained. In the second step, this method is used to design the IMC-PID controller of the TITO control system. The new auto-tuning scheme is implemented through the function code in typical DCSs (EDPF-NT, OVATION, Symphony, etc) and is used in 300MW fossil-fuel units. The industrial applications show that the scheme achieves better performance in specific load variation range.