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This article revisits the study of load frequency control (LFC) problem in an interconnected nonlinear power network under mismatched disturbance.Unlike previous works, a more realistic interconnected power network with nonlinear coupling between control areas and also including nonlinearities like generation rate constraint (GRC) and governor dead band (GDB) is under study. An adaptive super twisting sliding mode controller (ST-SMC) is designed based on system states and estimated disturbance. The nonlinear disturbance observer (NDO) estimates the mismatch between the electrical and mechanical power and then the estimated value is employed in the controller design to compensate the disturbance. The proposed control scheme ensures faster frequency and tie-line power stabilization compared with techniques existing in the literature. The robustness of the proposed design is validated under random varying step load disturbance and with two area four machine Kundur's test system. The closed loop system stability is theoretically proved using the Lyapunov function. Simulation results confirm the effectiveness of the proposed design in a two-area interconnected power network.

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The article addresses a generalized proportional-integral observer (GPIO)based event-triggered control (ETC) for load frequency problems in power systems with wind energy integration. The concept of static event-triggered mechanism (ETM) with a fixed threshold parameter may be unreasonable in some engineering applications where the transmission rates are time varying as in the case with power systems. Therefore, in this work, a dynamic ETM is designed to dynamically adjust the threshold parameters over time to reflect the time-varying transmission rates. The unmatched uncertainties are suppressed via high-gain design while the external disturbance (wind speed) is estimated and attenuated by the GPIO-based ETC. The proposed design ensures frequency and tie-line power stabilization and saves the computational and communication resources more effectively than recently reported works in the field. The hybrid closed-loop system's global bounded stability is theoretically proved and verified by simulation in three-area interconnected power systems. K E Y W O R D Sevent-triggered control (ETC), generalized proportional integral observer (GPIO), load frequency control (LFC), wind energy integration