Abstract: Voltage stability of Power system has become an issue for both power system planning and operation, because of a number of major black outs that have been experience in many countries by voltage stability problems [1, 2]. This has been mainly due to power systems operated closer to their stability limits . To determine voltage stability many studies have been carry out. In this study L-Index is use to calculate voltage stability of power system. References [3, 4] present comparative studies and analysis of six different voltage stability indices, while . Introduce the voltage stability L-index to be a simple but effective means of measuring the distance of a power system to its stability limit. Estimation of voltage stability by L-index in this study applied for monitoring voltage stability in a power system.
Keywords: Power system voltage stability, load flow, voltage stability line-index.