NERC PRC-023-6 Update and Lessons Learned

The Transmission Relay Loadability NERC Reliability Standard has been updated to revision NERC PRC-023-6. This update provides a significant change in the evaluation of out-of-step elements with the removal of Requirement R2. However, it may not be clear that even though this requirement was explicitly removed, the impact of out-ofstep blocking schemes on loadability is still expected to be evaluated for compliance with NERC PRC-023-6, Requirement R1. This paper provides an overview of the evaluation of out-ofstep blocking elements on transmission relay loadability pursuant to requirements of the NERC PRC-023-6 standard. Additionally, this paper provides lessons learned from work with Transmission Owners throughout the industry on best practices for relay loadability evaluation and common issues to look out for when evaluating compliance.