Assessment of component criticality in high voltage transmission stations

The issue of transmission system component criticality has received considerable attention at Hydro One in the last few years. Two reliability studies have been carried out: one to rank the components of sub-transmission systems and the other to rank the components of bulk transmission systems. In these two studies, probabilistic methods were used in ranking the components of the two systems. The various system components were ranked in accordance to some system performance criteria in terms of their relative importance to the overall system performance. A third reliability study has been performed recently at Hydro One to rank the various components of a high voltage transmission station in terms of their importance to the overall performance of the station. The station components are ranked according to some selected station performance criteria. The study results show that the ranking of station components depends on a number of factors such as the station performance criterion, station configuration, station component reliability, location of the component in the station layout and directions of flows on circuits emanating from the station. The purpose of this paper is to describe the study assessment methodology and its application to one of the Hydro One's high voltage bulk transmission stations.