A Simple Computation and Visualization of Voltage Stability Power Margins in Real-Time

This paper introduces a simple method to monitor
power system voltage stability conditions in real-time. The
method is based on the concept of Voltage Instability Predictor
(VIP). The essence of the method is a simple computation of a
voltage stability boundary based on VIP derived quantities. The
stability boundary is assumed as a parabolic equation in the P-Q
plane identified using measurements collected at a specific
substation, transmission path, or load center. The computed
stability boundary is further visualized in a P-Q plane, together
with a point representing the current operating conditions, and
generally re-computed as soon as the new set of measurements is
collected (preferably at high rates using phasor measurement
units). Simplicity and easy interpretation of the results brings
this method as a useful tool to increase system operator
situational awareness. Supporting results are provided using
relatively big test system (52 bus Nordic test system) and a real-life
system (a portion of the North-West USA system).