Assessment of North American Transmission Outages by Fault Type

This paper presents a first-of-its-kind analysis of the North American Electric Reliability Corporation (NERC) Transmission Availability Data System (TADS) outage data by fault type for transmission lines in the North American bulk electric system (BES) for both sustained and momentary outages from 2015 through 2018, including all the element types reported in TADS: alternating current (AC) circuits, direct current (DC) circuits, transformers, and AC/DC back-to-back converters. The paper covers an extensive spectrum of outage data attributes influenced by or correlated to fault type. Findings for automatic outages of all elements are presented. A deeper analysis of AC Circuit elements is also presented with statistically significant findings regarding voltage class, outage initiation code, outage mode code, initiating cause code, and outage duration. The analysis of outages and fault-type statistics contributes to improvements in power system planning and operations, including but not limited to: identifying weak points and reliability trends; targeting the development of design standards; compliance with planning and operating standards; and evaluating the effect of maintenance practices on reliability.