Leading causes of outages for transmission elements of the North American bulk power system

This paper presents results of the analysis of causes that initiate and sustain automatic transmission outages in the North American bulk power system (BPS). The study is based on the inventory and outage data collected from 2008 through 2014 in the Transmission Availability Data System (TADS) supported by the North American Electric Reliability Corporation (NERC). While causes of AC circuit outages on a North American scale have been investigated previously, this study presents results from the analysis of outages for the all elements types reported in TADS: AC circuits, DC circuits, transformers and AC/DC back-to-back converters. Top initiating and sustained causes differ by element type (e.g. Lightning as the leading initiating cause for AC circuit outages versus Failed AC substation equipment for transformer outages). Basic statistics on outage frequency per element and per hundred miles (for AC circuits and DC circuits) and outage durations are also provided.