Fractional Order PI Controller for Nonlinear Processes using Binomial Theorem Approximation

Abstract

In Most of the process industries, Integer order Proportional Integral controller (IOPI) has been designed for different processes due to its simplicity but it will damage the final control element due to the sudden change in controller output. So, this research work proposed to eliminate the ringing phenomena by applying large pure time delay in the controller output by proposing Fractional Order Proportional Integral (FOPI) controller using Binomial theorem approximation for the nonlinear conical and spherical tank level processes. The control of liquid level in the nonlinear tank is arduous in nature due to an imbalance in the area of the transverse section of the tank. The robustness of the IOPI and FOPI controllers has demonstrated in Time Domain Specifications (TDS). The FOPI controller eliminates the peak overshoot in the process variable and ringing effect in controller output to protect the pneumatic positioned control valve.