Analysis of Voltage Collapse in a Power System Using Voltage Stability Indices

Abstract

Voltage collapse phenomenon and its incessant occurrence in a modern power system has of recent been a great concern to power system utilities. The aftermath of which could be very devastating and detrimental to the optimum operation of a power system. Thus, it becomes imperative to identify the most vulnerable bus to voltage collapse by power system operator to prevent outages and blackout that may result. Presented in this paper are techniques based on the use of voltage stability index (L-index) and voltage collapse proximity index (VCPI) to identify a voltage collapse bus. First, the basecase values of the L-index and VCPI for all the load nodes are evaluated. The system is then subjected to a gradual reactive power load change to determine the voltage collapse bus. The bus with the maximum value of L-index and VCPI is taken as the critical bus liable to voltage collapse. The effectiveness of the methodology is tested on the Southern Indian 10-bus and IEEE 14 bus power systems. Result obtained shows that the use of the techniques of L-index and VCPI in the identification of critical node in a power system could be of great benefit to the power system operation and planning.

Keywords: Voltage stability, Voltage collapse, L-Index, VCPI, power flow, power system