Probabilistic Assessment of Transient Stability in a Practical Multimachine System

The application of probabilistic techniques in the quantitative evaluation of power system reliability is steadily increasing. Probability methods are being used extensively in the assessment of static adequacy. Their application to the evaluation of transient or dynamic phenomena has not yet, however, been widely utilized. The probabilistic nature of the transient stability problem and the inclusion of the probabilities associated with the initiating factors such as the type, location and clearance of faults in the analysis of a simple single machine-infinite bus system has been demonstrated in a recent paper.1 The present paper addresses the problem of transient stability analysis in a practical multimachine system from a probabilistic view-point. The basic concepts developed in Reference ! are applied to a simplified 33 bus model based on the Saskatchewan Power Corporation (SPC) system, to demonstrate the technique of considering the probabilities associated with the occurrence and clearance of faults. Transient stability indices for each line, for different types of faults and a single stability index for any fault are obtained. A single stability index for the overall system is evaluated for different fault types and amy fault using actual system outage statistics. The effect of fault clearing and reclosing times on the system stability is investigated for the most critical line in the system.