Int. J. Power and Energy Conversion, Vol. 7, No. 2, 2016 139 Copyright © 2016 Inderscience Enterprises Ltd. Application of multi-objective PID controller for load frequency control in two-area nonlinear electric power systems Magdy A.S. Aboelela Department of Electrical Power and Machines, Faculty of Engineering, Cairo University, Egypt Email: aboelelamagdy@yahoo.com Abstract: Design of optimal controllers is indeed a multi-objective optimisation problem. Non-dominated sorting in genetic algorithms-II (NSGA-II) is a popular algorithm for solving multi-objective optimisation problems. This paper investigates the application of NSGA-II technique for the tuning of a proportional-integral-derivative (PID) controller for a class of identical two area-thermal power stations including the generation rate constraint (GRC) and boiler nonlinear dynamics as well as the governor dead band (GDB). The design objective is to improve the damping of frequency fluctuation in two-area power system when subjected to a disturbance in their loads. The proposed technique is applied to generate Pareto set of global optimal solutions to the given multi-objective optimisation problem. Further, the two PID controllers in each area are assumed to have identical structures (same parameters). Simulation results using the tuned multi-objectives-based GA PID controller are presented. The effectiveness of the proposed scheme is confirmed using MATLAB-Simulink software. Keywords: load frequency control; LFC; electric power system; PID controllers; multi-objective genetic algorithm; nonlinear systems. Reference to this paper should be made as follows: Aboelela, M.A.S. (2016) ‘Application of multi-objective PID controller for load frequency control in two-area nonlinear electric power systems’, Int. J. Power and Energy Conversion, Vol. 7, No. 2, pp.139–156. Biographical notes: Magdy A.S. Aboelela received his BSc and MSc degrees from Cairo University (Egypt) in 1977 and 1981. He received his PhD degree from the State University of Ghent, Belgium in 1989. He is currently working as a Professor at Cairo University. He has worked as a Visiting Professor at Ilorin University, Nigeria and Sultan Qaboos University in Oman. His interests are artificial intelligence, automatic control systems, stochastic modelling and simulation, decision support systems, management information systems, and application of computer technology in industry. He has published more than 70 scientific articles in journals and conference proceedings. 1 Introduction Despite significant strides in the development of advanced control schemes over the past three decades, the classical proportional-integral-derivative (PID) controller and its