Analysis and control of inter-area oscillations for system security enhancement

Low frequency inter-area oscillations of 0.1-0.8 Hz have been observed in many power systems, generators in one area oscillating against those in another. In this paper the factors controlling the damping of these oscillations are determined with reference to an 8-machine system shown. The action of a controllable phase shifter in one of the tie-lines between the areas in stabilising the system is explored. Fuzzy logic control is shown to give the phase shifter a very good damping action. Time-domain and eigenvalue analysis are used to examine the system dynamics, and participation factors are used to detect the machines most heavily involved. The modes with least damping are of greatest interest.