A Comparison of Voltage Stability Indices for Critical Node Identification in a Power System

Recent incidence of voltage collapse in some developed and developing nations across the globe has caused a huge risk to electrical power industries. Consequently, it becomes imperative to identify suitable method that can be used for the assessment of voltage stability (VS) in such a system. In this paper, the voltage stability indices such as L-Index, Voltage Collapse Proximity Index (VCPI), Novel Line Stability Index (NLSI), Fast Voltage Stability Index (FVSI) and the Bus Participation Factor (BPF) are compared together. To do this, for the L-Index, VCPI, NLSI and FVSI methods, the system is made to undergo a slow variation in reactive power load at each load bus until a voltage collapse point is reached. The load node with the highest value of L-Index, VCPI, NLSI and FVSI is picked as the voltage collapse bus. The values of BPF for each load node is calculated based on the critical mode, right and left eigenvectors of the system. The usefulness of all the methodologies is tested on the Southern Indian 10-bus and the IEEE 5-bus power systems. Result obtained shows that the use of BPF can be of great significant in the investigation of voltage stability compared with other methods.