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