SET POINT TRACKING CAPABILITY ANALYSIS FOR AN INDUSTRIAL IPDT PROCESS MODEL

Abstract

In this paper the Proportional integral controllers based on Internal Model Control principles tuning technique for a pure integrating process with dead time is designed. The performance of these controllers with different closed loop time constants is analyzed and compared for its set point tracking capability. The controller with best performance for the selected time constant is decided. Every tuning procedure is centered on process model. The understanding of the operator who knows how the plant responds to the different inputs is the simplest model. Neglecting model uncertainty leads controllers unstable in the real world operations. The input is to be decided according to their importance. Finally the design specifications are given for good performance(1). A process model is a set of equations including the necessary input data to solve the equations that allows us to predict the behaviour of a chemical process system(2).The process whose model to be prepared may be with time delay or without time delay. The processes with time delay are the complex processes which are difficult to analyze .The delay time in the process is due to the transportation lag i.e. delay is always present with movement and due to the location of the sensors. The delay in the process may also be caused due to the delay in any part of the system. The delay in the process creates a serious problem in the designing process control system. The system with time delay are difficult to analyze and can be classified as first order plus dead time (FOPDT),second order plus dead time (SOPDT) and integral plus dead time (IPDT). The time delay present in the process can be approximated by different approximating techniques like Taylor's approximation, Pade's approximation etc. �