ABSTRACT
This paper presents a novel system stabilizer based on type-2 adaptive fuzzy sliding mode approach without reaching phase and chattering for a nonlinear power system. Low frequency oscillations of small magnitude linked with the electromechanical models in power systems, often persevere for long periods and may in some cases drastically hinders power transfer capability. These oscillations may occur locally or inter-power areas, due to in a large part to the difference in generators inertia constants of weakly linked power areas. Robustness of power availability can therefore be jeopardized. To help prevent these oscillations from limiting power flow, we present a new sliding mode based power system stabilizer with a sliding surface such that the system is always on the sliding surface and hence improve the system robustness. Furthermore, to account for rapidly changing operating conditions we use two adaptive Type-2 fuzzy systems to approximate the unknown power system nonlinear dynamics. To overcome the presence of chattering, we use a modified control signal. Stability is insured through Lyapunov synthesis. Severe operating conditions are used in a simulation study to test the validity and effectiveness of the proposed method which indicates good performance and satisfactory transient dynamic behaviour. A multi-machine power system is used to demonstrate the performance of the proposed controller and its superiority over conventional stabilizers used in the literature.
