A simple computation and visualization of voltage stability power margins in real-time

Abstract

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).