Study on PID controller design and performance based on tuning techniques

The simplicity, ease of implementation and robustness has attracted the use of Proportional, Integral and Derivative (PID) controllers in the chemical process industries. Numerous tuning techniques are available for tuning of PID controllers, each one of it has its pros and cons. Majority of the tuning techniques are proposed for First Order System with Time Delay (FOPDT). This paper presents the technique for obtaining the FOPDT model using Sundaresan and Krishnaswamy method and performance comparison of PID controller based on open loop, closed loop tuning techniques and PID controller tuned with Internal Model Control (IMC) technique for setpoint tracking and disturbance rejection. Analysis is carried out in terms of Integral error criteria's, Integral Absolute Error (IAE) and Integral Squared Error (ISE) and time response information viz. rise time, settling time, % peak overshoot and maximum sensitivity. Superheated steam temperature system of 500 MW boiler and Mean arterial blood pressure system are considered for the simulation study. The results indicate that the ratio of time delay and time constant have influence on the performance of the tuning techniques. IMC - PID provides the flexibility of adjustment for desired performance in comparison to other tuning techniques.