IMPROVEMENT OF POWER SYSTEM STABILITY BY MEANS OF STATIC VAR COMPENSATOR.

Thyristor-controlled static var compensators (SVC) are now being used in several power systems all over the world for improving power system stability and suppressing voltage variations. In this paper, the authors discuss how much capacity of SVC should be installed for improving stability. Three model systems (2 one-machine infinite-bus systems and 1 longitudinal system) are used for the study. The study is carried out using experimental networks and by computer simulation. It is concluded that SVC is more effective to the longitudinal system than to the one-machine infinite-bus system. It is demonstrated by digital simulation that the longitudinal system can be stabilized very effectively by SVC. Many control schemes of SVC (e. g. , constant voltage control, tie line power differentiation control, reactive power open-loop control) so far have been proposed. However, it is assumed in this paper that SVC is always under constant voltage control.