Optimal Frequency Regulation Control Based on Nonlinear Hybrid Controller for Iraqi Interconnected Power System

This study investigates critical challenges associated with Load Frequency Control (LFC) in interconnected power system using a realistic model of the Iraqi three-area interconnected power system. In this paper, these areas include the power system northern, central, and southern regions each comprising different power sources generation, including hydro, thermal, gas, and diesel units. The model is calibrated based on physical real data supplied by the ministry of electricity in Iraq. In addition, this study considers improving the performance of the nonlinear conventional fractional sliding mode controller by incorporating an additional switching function alongside with the traditional switching function to mitigate the steady-state error and oscillations accompanying the LFC system. Thus, the modified controller is hereafter called Hybrid Optimized Fractional Order Sliding Mode Controller (HOFOSMC) used to control the frequency and the power shared by the tie-lines of Iraqi three areas interconnected power system model. The proposed controller is analysed under various load disturbances and system parameters uncertainties. Simulation results demonstrate, under a 15% ramp load disturbance, HOFOSMC reduces the maximum frequency deviation by up to 60% compared with OFOSMC and approximately 83% compared with OSMC, while also shortening the settling time by 60% and 83%, respectively. Furthermore, under stochastic white-noise disturbances, HOFOSMC achieves reductions of up to 33% and 56% in peak frequency deviations, along with corresponding reductions in settling time, relative to OFOSMC and OSMC. These results confirm the superior robustness, faster damping, and enhanced stability of the proposed HOFOSMC for LFC of the Iraqi three-area interconnected power system.