A NEW INDEX FOR ONLINE MONITORING OF VOLTAGE STABILITY IN POWER SYSTEMS

This paper presents a new line voltage stability index for voltage stability assessment. The proposed index is easy to compute and based on voltage phasors of sending and receiving ends of the line and can be used for online monitoring of power systems provided that lines must have phasor measurement units installed at both ends. It is based on the fact that, at critical loading (Collapse point), the determinant of line flow Jacobian is zero. Proposed index approaches to unity at critical loading. The proposed index is computed under three different directions of load increase and it is compared with well established line index L [34] for validation. Further, the index has been tested for IEEE 25 bus test system and characteristics based scheme with newly developed index has been proposed for prior detection of voltage collapse and for taking countermeasures against it. The results obtained show the usefulness of proposed index for online applications.