Effective Open-loop Transfer Function method for design of multi-loop PI/PID controller for interacting multivariable processes

In terms of control multi loop processes are very complicated when compared to single loop processes due to the existence of interactions between manipulated and controlled variables. During the last several decades this topic has drawn lot of research attention and many multivariable control approaches have been proposed. This Project proposes an Effective Open-loop Transfer Function (EOTF) method for PI/PID design of multi-loop control processes, by employing the concepts of Internal Model Control (IMC) with reduced EOTF and Dynamic Relative Gain Array (DRGA). With this method a multiloop control system is decomposed into a set of independent single input single output (SISO) loops. The advantages of the proposed method are: (i) the overall control system performance is better compared with existing methods, and (ii) the control system is robust. This technique works with satisfactory performance even under significant model mismatches that commonly occur in the process control industry. With the help of Effective Open-loop Transfer Function (EOTF) - based method and DRGA concept, dynamic interactions are satisfactorily taken in to account. Benchmark examples of multivariable industrial processes with different interaction characteristics are used in this paper to demonstrate the simplicity and effectiveness of the proposed design method. The proposed method is simulated using MATLAB/SIMULINK.