Related Files
Status
The informal comment period for the Project 2021-05 Modifications to PRC-023 Standard
Authorization Request concluded 8 p.m. Eastern, Wednesday, July 28, 2021. Once a drafting team is formed, the comments will be
reviewed and the next steps of the project determined.
Background
Requirement R2, in PRC-023-4, requires applicable functional entities to set their Out of Step Blocking[1] (OOSB) elements to allow tripping for faults during the loading conditions prescribed by Requirement R1. A requirement to allow tripping in a Standard whose intent is to block tripping, has led to some entities disabling their OOSB relays. Disabling of these relays could lead to tripping during stable power swings causing an increased reliability risk. OOSB relays provide increased security by preventing relays from tripping for stable power swings. Preventing the tripping of transmission lines during these types of disturbances increases the reliability of the BES. Requirement R2 should be removed because it has been interpreted to restrict the setting of OOSB elements making compliance with PRC-026 more difficult.
Attachment
A exclusion 2.3 should also be removed. This exclusion is no longer needed and
that exclusion has contributed to the confusion surrounding R2. Attachment A
exclusion 2.3 has been interpreted as being in conflict with R2. Both R2 and
Attachment A exclusion 2.3 are not needed in the Standard.
Standard(s) Affected: PRC-023-4
Purpose/Industry Need
The purpose of the proposed project provides a reliability-related benefit by eliminating PRC-023-4 Requirement R2. This will eliminate entities disabling their OOSB elements unnecessarily. It will remove an unnecessary exclusion (Attachment A – 2.3) for relays that no longer need an exclusion.
[1] The term power swing blocking (PSB) is also used by industry to describe these elements.
