FERC Proposes to Approve Regional Underfrequency Load Shedding Reliability Standard
Friday, October 5, 2012

In a Notice of Proposed Rulemaking issued on September 20, 2012, FERC proposed to approve the Northeast Power Coordinating Council’s (NPCC’s) Regional Reliability Standard on Underfrequency Load Shedding (UFLS). The proposed PRC-006-NPCC-1 Regional Reliability Standard (Regional Standard) would address declining system frequency events in coordination with the existing continentwide PRC-006-1 UFLS Standard.

The Regional Standard contains 23 requirements, including a threshold for setting underfrequency trip protection for generators in the NPCC Region. The Regional Standard follows the existing NPCC Directory #12 Underfrequency Load Shedding Program Requirements, which have governed NPCC’s automatic UFLS programs since 2009. The Regional Standard is intended to accommodate the differences in transmission and distribution topology between NPCC Planning Coordinators caused by their historical design criteria, their load demands, and their generation resources. FERC concluded that the Regional Standard is stricter than the continentwide standard because it provides more specific requirements, such as a requirement for nonnuclear owners to have compensatory load shedding to compensate for the loss of their generation due to early tripping.

FERC sought comments on (1) the technical basis for the 57.8 Hz maximum tripping limit for existing nuclear units established in requirement R19 and (2) the timeframes for actions that result in changes to the NPCC UFLS program.

FERC proposed to approve the effective dates requested by NERC. Requirements R1 through R7 would become effective on the first day of the first calendar quarter after regulatory approval, but no earlier than January 1, 2016, to accommodate the six-year implementation period in NPCC Directory #12. Requirements R8 through R28 would become effective on the first day of the first calendar quarter two years after regulatory approval.


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