Background: This paper presents a novel optimized Fractional-Order Proportional-Integral
Derivative (FOPID) controller for controlling the terminal voltage of an automatic voltage regulator
system. The parameters of the proposed controller are optimized using a recent meta-heuristic technique
known as Grey Wolf Optimizer (GWO).
Methods: A recent meta-heuristic technique known as Grey Wolf Optimizer (GWO) is used for fine
tuning of FOPID controller parameters. Initial values of proportional gain (Kp), integral gain (Ki), and
derivative gain (Kd) of the controller are tuned using Ziegler-Nichols (ZN) method where values of λ
and µ are chosen randomly. A nonlinear fitness function consisting of rise-time, settling-time,
maximum-overshoot and Integral of Time Square Error (ITSE) has been chosen as the fitness function
for the proposed algorithm to get the optimum solution.
Results: The proposed FOPID controller provides faster response (i.e. minimum rise-time (0.0292
sec.)), minimum settling time (0.1107sec.) and desired frequency domain characteristics (Gain
margin=25.2, Phase margin=60.2).
Conclusion: The proposed FOPID controller provide faster and better control action for AVR system.
Additionally, it also improves the robustness of the system with respect to model uncertainties.
Simulation results are validated with the existing techniques in the literature with the help of figures and
also summarised in tables.