1995 Volume 115 Issue 9 Pages 1054-1063
A static Var compensator (SVC) can improve the steady-state stability (or the small signal stability), if it is located appropriately. The present paper proposes a method for selecting the best siting of SVC in large scale power systems for damping effectively.
Conventionally, it is thought that SVC improves steady-state stability by its voltage regulating ability. From this point of view, the stability can be improved significantly if SVC is located at the bus which has a large voltage fluctuation due to the lightly-damped power swing mode. In contrast to the conventional viewpoint, the present paper makes it clear that the steady-state stability deteriorates by the conventional voltage regulating control of SVC in some cases. Therefore, the voltage fluctuation is not appropriate index for effective damping.
The present paper explains the mechanism of improvement of steady-state stability by SVC in terms of the modal analysis. On the basis of the modal analysis, an index for determining the location of SVC is derived. The index is called LIED (Location Index for Effective Damping) by the authors. Digital simula-tions are conducted for an 8-machine longitudinal system and a 29-machine looped system to demonstrate the validity of the proposed index.