Identifying electrically weak and strong segments of a power system from a voltage stability viewpoint

Voltage instability leading to collapse appears to be due to the inability of networks to meet a demand for reactive power at certain critical (or weak) buses. Practical control algorithms to prevent voltage collapse should identify the critical buses in the network and maintain control on voltages at these buses in particular. Two methods are proposed for identifying the weak buses and segments in power transmission networks. Both methods employ a technique for determining the static voltage stability limit in multimachine power systems. The first method is based on the relative change in the bus voltages going from an initial operating state to the voltage stability limit. The second method is based on the sensitivity parameters computed at the voltage stability limit