Voltage security assessment and vulnerable bus ranking of power systems

The voltage stability problems, usually resulting from system heavy loading, are an indispensable aspect of power system stability. The method proposed in this paper is able to evaluate voltage stability status efficiently in both pre-contingency and post-contingency states using two outstanding techniques, adapting the continuation method and the local analysis of contingency effect. Also, to overcome voltage security problems, it is essential to recognize vulnerable areas of the power system. The proposed method is also able to determine vulnerable buses of the power system from the viewpoint of voltage security by determining the best candidates for the start point of the voltage collapse phenomenon. Results of testing the proposed methods on two practical systems, power networks of New Zealand and Iran, confirm the validity of developed approaches. (C) 2002 Elsevier Science B.V. All rights reserved.