Power system reliability based on voltage weakest bus identification

The weakest bus in a network is the first point where voltage collapses in a severe contingency. The weakest bus may change with system configurations and operating conditions. This paper proposes a technique to evaluate the weakest bus and system reliability based on system voltage stability under various system contingencies and operation conditions. A power system is divided into safety, margin, risk, and collapse zones according to the practical voltage limitations and voltage collapse point. The three voltage collapse indicators of Minimum Voltage Index (MVI), voltage change index (VCI) and voltage collapse proximity indicator (VCPI) are adopted for determining the voltage distance to the collapse point and weakest bus identification. The IEEE 30-bus system has been modified and analyzed to illustrate the proposed technique. The results provide system planners and operators very important information for the weakest points at different contingencies.