Voltage stability assessment using Phasor Measurement technology

The Phasor Measurement Units (PMU) installations worldwide along with the advancements in computing and communications enabled the time tagged phasor measurements of voltages and currents. These real time phasor measurements have become the backbone of wide-area monitoring, protection, and control for various applications in power systems. This paper highlights the monitoring of voltages and phase angles across different nodes that provides very useful information indicating the system state and its proximity to stability limit. The most crucial task is placement of PMUs at minimum number of buses for complete observability. Recursive spanning tree algorithm of PSAT is applied to find out the minimal placement locations for observability of all buses. The Thevenin's equivalent parameters have been obtained from the measured and estimated voltages at the load buses and impedance matrix Zbus. The parameters obtained are used to find the voltage stability boundary. Results on IEEE-14 bus system and IEEE-30 bus system are presented to illustrate the proposed approach.