  The short-term voltage stability (SVS) problem in large-scale receiving-end
power systems is serious due to the increasing load demand, the increasing use
of electronically controlled loads and so on. Some serious blackouts are
considered to be related to short-term voltage instability. In China, the East
China Grid (ECG) is especially vulnerable to short-term voltage instability due
the its increasing dependence on power injection from external grids through
HVDC links. However, the SVS criteria used in practice are all qualitative and
the SVS indices proposed in previous researches are mostly based on the
qualitative SVS criteria. So a Short-Term Voltage Stability Index (SVSI), which
is continuous, quantitative and multi-dimensional, is proposed in this paper.
The SVSI consists of three components, which reflects the transient voltage
restoration, the transient voltage oscillation and the steady-state recovery
ability of the voltage signal respectively after the contingency has been
cleared. The theoretical backgrounds and affected factors of these three
components of SVSI are analyzed, together with some feasible applications. The
verification of the validity of SVSI are tested through more 10,000 cases based
on ECG. Additionally, a simple case of selecting candidate locations to install
dynamic var using SVSI is presented to show its feasibility to solve the
optimization problem for dynamic var allocation.
