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

This paper presents the results of a probabilistic transient stability asse ssment conducted on the large scale system of B.C. Hydro, including a gener ation rejection study on the Peace system and a transfer limit study on the Columbia system. In these studies, B.C. Hydro's historical statistics on t he probabilistic states of load level factor, fault type, fault location, f ault clearing, and automatic reclosing were used in a Monte Carlo formulati on to generate sample states for the studies. For each study, 1000 cases we re generated for which the transient stability limits were calculated using a modified shell of B.C. Hydro's on-line transient stability program. The shell which was developed for this project uses PTI's PSSE simulation progr am 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 deter ministic criteria do not always correspond to the "worst case" as it is nor mally assumed.