Abstract
The main purpose is to evaluate the effectiveness of SVC installation from the viewpoint of an energy-based index. Although transient and voltage stability - due to distinct mechanisms and separate time frames - have been perceived as decoupled phenomena by some researchers, in this work they are treated as aspects of coupled power system dynamics. The time-domain simulation uses detailed models for system components and controllers including SVC. Based on the trajectories obtained, an energy value can be calculated for every point in time. The energy function formulation is developed using injection models. The measure of stability used is the energy margin. This is computed based on the well-known second-kick method. A new second-kick design better suited for exploring voltage instability mechanisms is proposed, which consists of a combination of load step and fault. The better timing of applying a second-kick disturbance is also studied. Results are shown for a standard IEEJ test system. Energy margins and unstable equilibrium point approximations are calculated for the conventional and new second-kick designs. It is seen that the energy margin is dependent on the nature of the disturbance. SVC's are expected to improve stability by providing fast reactive power support at key load buses. Improved energy margins are observed when these devices are available.
