Assessments of Power Systems Voltage Stability Considering Transmission Line Security

This paper presents two indicators, namely line voltage stability and line ampacity indices, to determine the voltage stability states and line security of power systems under various operating conditions. Both indices rely on the measured values that are already obtained from conventional measurements used in power systems. The identification of weak buses and critical lines based on the proposed indices is possible using only voltage magnitude and real power measurements. To validate the effectiveness of the proposed indices, two power networks have been tested under increasing system loading and line outage conditions. Numerical experimental results indicate that by considering both line voltage stability and line ampacity indices, power systems could mitigate the risks of voltage collapse and excessive current in transmission line.