Fractional Order PID Controller for Minimizing Frequency Deviation in a Single and Multi-area Power System with Physical Constraints

Abstract

In this paper, a Fractional Order PID (FOPID) controller to minimize frequency deviation in a single and two area power system is presented. Minimizing high frequency deviation in the presence of physical constraints is very paramount in load frequency control. This is because large frequency deviation can cause the transmission line to be overloaded which may damage equipment's at the generating and distribution level. In this paper, power system with Communication Delay, Governor Dead Band and Generation Rate Constraint were considered and modeled appropriately. An anti-windup scheme was employed to limit the effects of these physical constraints on the power system. The proposed FOPID was designed using the Fractional Order Modeling and Control toolbox available in MATLAB/Simulink. Antlion Optimization algorithm was used to optimize the gains of the FOPID controller by minimizing Integral Square Error as the objective function. The Integral Square Error to be minimized is the summation of the errors in frequency deviation, tie-line power deviation and the area control error. Simulations were first conducted on power systems designed without physical constraints, and results obtained outperformed other designed methods available in literature for one and two area power systems. Three physical constraints were then added to the power system. The proposed methods outperformed other designed method in minimizing frequency deviation, tie-line power deviation and area control errors. However, the proposed FOPID controller took a longer time to balance the generated power and load demand when compared to other designed methods for power systems without physical constraints.