Local Voltage-Stability Margin Based on Short-Circuit Capacity

Short-circuit capacity is a usual measure of voltage strength of a bus. A new localvoltage-stability margin based on the derived relation between voltage stability and short-circuit capacity is proposed in this paper. The proposed margin makes it possible to take distribution network into consideration by applying the newly developed synthesis load model with distribution network. And its on-line determination simply requires some locally measurable quantities, such as bus voltage magnitude, and active and reactive components of bus load. The effect of any change in system operation condition is fully exploited by this margin. The simulation on the New England 39-bus system indicated that the proposed margin can correctly identify the weakest bus causing voltage instability of power system for various conditions.