IMC Based Design of PI Controller for Real Time Pressure Process

Abstract

Abstract:The objective of the work is to maintain the pressure in the closed loop at desired set value. The pressurized tank has the features of nonlinearity, sluggishness by tuning conventional PI methods. This paper focus on implementation of internal mode control (IMC) to obtain an optimal PI control setting for pressure process. System identification of the process is done by process reaction curve method. To improve the robustness, internal model control method (IMC) is employed in tuning the PI controller and is applied to the First Order plus Time-Delay (FOPTD) model. Here delay is approximated with First Order plus Pade Approximation. At first, a Proportional Integral (PI) controller based on IMC-PI setting is designed and the results are compared with Ziegler Nichols (ZN) controller settings. The robustness of the controllers are endorsed by imposing both servo and regulatory disturbances. The simulation results confirm that IMC-PI controller has improved dynamic performance on disturbance rejection.Keywords: IMC, Ziegler Nichols, PI controller, Pressure process. I. INTRODUCTIONThe PI control is the most commonly application of control strategy nowadays, with its simple arrangement, good robustness and wide application range, it is gradually highlighted in the control theory. It has been observed that, however, the existing PI controllers may not perform well in the complex control processes, such as the higher-order system and time-delay system. Efforts have been put to fix this problem, and numerous effective PI controller design and tuning methods for complex processes have been stated [1] PI tuning has certainly been the key to reasonable performance and robustness. PI controller setting is proposed for several process model, especially for First Order plus Time Delay (FOPDT). There are two commonly used method of PI tuning, they are ZieglerNichols setting [2] and Cohen-coon setting [3], which still used in several industrial applications. Internal Model Control [4] allow system designer to specify the anticipated system behaviour. The robustness and performance of the model can controlled by the single parameter (λ). IMC-PI setting is one of the greatest closedloop method among experts and researchers since it is the easy way to understand. In the context of IMC, Parameter of consequent close-loop models are enhanced with respect to error performance criteria such as Integral of Time Weighted Absolute Error (ITAE) [5], Integral Square Error (ISE) and Integral Absolute Error (IAE). The Internal Model Control (IMC) structure offers an appropriate structure for satisfying the ideas. IMC [6] theory has been used earlier and autonomously by a number of other scholars. Using the IMC setting design technique, controller difficulty depends entirely on two factors: the difficulty of the model and the performance necessities indicated by the designer. IMC denotes to a methodical technique for control design based on the Qparameterization [7] idea that is the source for many current control methods. IMC offer...