Decentralized LMI-based event-triggered integral sliding mode LFC of power systems with disturbance observer

In this paper, a disturbance observer (DO)-based event-triggered integral sliding mode control (DOETISMC) scheme for load frequency control (LFC) is presented in the presence of time varying uncertainties and disturbances. Firstly, the disturbance observer is designed to provide an online estimation of the unmatched load disturbance from the measurable variables. This estimation is being used as a feed-forward to the controller to attenuate the disturbance effect. Secondly, two types of integral sliding surfaces are proposed based on the estimated disturbances to eliminate the chattering effect of the integral sliding mode control (ISMC). Due to Lyapunov theory and utilization a decreasing triggering threshold, the ultimate boundedness stability of the system under the proposed controller is proved. Moreover, it is ensured that during the system process, the Zeno event as a basic obstacle in the ETISMC does not occur. The validity and advantages of the proposed method in oscillation suppression are well revealed through numerical simulations in different cases of single-area and multi-area power systems with time varying uncertainties and disturbances.