Large scale probabilistic transient stability assessment using BC Hydro's on-line tool

This paper presents the results of a probabilistic transient stability assessment conducted on the large scale system of BC Hydro, including a generation rejection study on the Peace system and a transfer limit study on the Columbia system. In these studies, BC Hydro's historical statistics on the probabilistic states of load level factor, fault type, fault location, fault clearing, and automatic reclosing were used in a Monte Carlo formulation to generate sample states for the studies. For each study, 1000 cases were generated for which the transient stability limits were calculated using a modified shell of BC Hydro's on-line transient stability program. The shell which was developed for this project uses PTI's PSSE simulation program and the Second Kick method. The results obtained showed that BC Hydro's existing deterministic criteria are very conservative with a probability of instability of smaller than 0.2%. The studies also revealed that the deterministic criteria do not always correspond to the "worst case" as it is normally assumed.