Load frequency regulation using observer based non-linear sliding mode control

In this paper, the generalized extended state observer (GESO) and non-linear sliding mode control (SMC) are merged together to study the frequency deviation problem in multi-area power system. In study, the GESO is used not only for state and disturbance estimation but also for disturbance rejection of the system. The said observer ensures accurate estimation of the actual states leading to convergence of estimation error to zero. The non-linear SMC is used to increase the damping ratio of the system whenever, any perturbations occurs. The proposed observer based controller is compared with an existing two-layer active disturbance rejection control (ADRC) and also validated on large power system at random load disturbance. Further, the proposed controller performance is tested on the minimum and non-minimum phase systems. In addition to fast response in terms of settling time and reduced over/undershoots, the proposed control scheme satisfactorily compensates the disturbance in the system. The proposed scheme is further tested in the presence of power system non-linearities such as generation rate constraints and governor dead-band. The simulation results illustrate the robustness of proposed controller when subjected to load disturbances and non-linearities.