This study reports on the results from efforts by the Institute of Electric and Electronics Engineers (IEEE) DistributionReliability Working Group (DRWG) and the U.S. Energy Information Administration (EIA) to improve the usefulness of reliabilitymetrics by developing and then applying consistent, yet distinct measures of the continuity of supply based on the portion of theelectric power system from which power interruptions originate: the lower voltage distribution system versus the high-voltagebulk power system. The modified metrics better support reliability planning in the US because they separately measure theeffectiveness of actions to improve reliability made by the two distinct groups of firms (and their regulators or oversight bodies)that are responsible for planning and operating each portion of the US electric power system. The authors then present for thefirst time quantitative information on the reliability of each portion of the US electric power system. When reliability is measuredusing the system average interruption duration index and the system average interruption frequency index, they find that thedistribution system accounts for at least 94 and 92%, respectively, of all interruptions. They also find that these relationshipshave been stable over the recent past.
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This is an open access article published by the IET under the Creative Commons Attribution-NonCommercial-NoDerivs License (http://creativecommons.org/licenses/by-nc-nd/3.0/)