A new approach for real-time voltage stability monitoring using PMUs

This paper proposes a new approach using phasor measurement units (PMUs) to estimate real-time voltage stability margin for a load area supported by multiple tie lines. For the monitored tie lines, it can provide accurate real and reactive power transfer margins. Compared to a traditional Thevenin equivalent-based approach, the new approach is more tolerant of fluctuations in the phase angles of the external system and the power factors of tie-line flows. A two-bus power system and the IEEE 39-bus system are used to test this new approach and compare it with the traditional approach.