It has become an important task for many voltage stability studies to find a
voltage stability index. The voltage stability indices provide reliable information
about proximity of voltage instability in a power system. In this paper, the L
indicator has been proposed, which aims to detect the weakest load buses in the
electrical power networks. The L indicator has been checked by its application to
the (WSCC 9-bus and IEEE 14-bus) test systems. Finally, the proposed indicator
has been applied to the Iraqi power grid (400 kV) considering different
contingencies, such as lines outage, generated power reduction and loading
increase. The short computation time of this indicator and its efficient detection of
the weakest load buses in the Iraqi power grid, allow the operators to apply it in online
voltage stability monitoring based on measurements.