Design of Adaptive Power System Stabilizer for Damping Power System Oscillations

Abstract

Power systems are subjected to low frequency disturbances that might cause loss of synchronism and an eventual breakdown of entire system. The oscillations, which are typically in the frequency range of 0.2 to 1.0 Hz, might be excited by the disturbances in the system or, in some cases, might even build up spontaneously. These oscillations limit the power transmission capability of a network. For this purpose, Conventional Power System Stabilizers (CPSS) are used to generate supplementary control signals for the excitation system in order to damp these low frequency power system oscillations. The use of power system stabilizers has become very common in operation of large electric power systems. The conventional PSS which uses lead-lag compensation, where gain settings designed for specific operating conditions, is giving poor performance under different loading conditions. The constantly changing nature of power system makes the design of CPSS a difficult task. Therefore, it is very difficult to design a stabilizer that could present good performance in all operating points of electric power systems. This thesis aims to propose a design of power system stabilizer based on model reference adaptive control to overcome drawback of conventional Power System Stabilizer. In this design, the existing controllers, designed using gradient descent algorithm and lyapunov method. The Adaptive Power System Stabilizer and Conventional Power System Stabilizer are evaluated on a single machine infinite bus system and three machines nine bus system by eigenvalue technique and time domain simulation using Matlab/Simulink. The simulation studies have been done to evaluate the effectiveness of the proposed control design. The results show that, the proposed adaptive power system stabilizer control scheme is able to stabilize power system oscillations under the changeable operation conditions than the Conventional Power System Stabilizer.