March 12, 2019

The NATF has posted the “Relay Performance During Stable Power Swings (PRC-026-1) Evaluation Tools Reference Document” to our public website for industry use. 

NERC Reliability Standard PRC-026-1, “Relay Performance During Stable Power Swings,” requires utilities to evaluate the performance of various load-responsive protective relays in response to stable power swings during non-fault conditions.  Impedance-based relays are evaluated against a power swing region defined by the standard.  This evaluation is unlike any analysis currently performed when setting most impedance-based relays.  Thus, new power swing analysis functions are needed within commercial protection system analysis tools, or utilities must develop custom calculators using general-purpose spreadsheets or engineering calculation software.

This document lists functional attributes for either type of tool.  Tool developers may reference this list when developing software requirements specifications.