What situation necessitates a corrective action plan to be submitted to the local Regional Reliability Organization?

A corrective action plan is required when significant operational issues or events occur that could impact the reliability of the power system. In this scenario, the situation involving transformer differential relay operation with a simultaneous line ground fault represents a serious operational concern. Such events can indicate underlying problems in the system that may lead to failures or outages if not addressed promptly.

When differential relay operations occur, it typically means that there has been an abnormal condition within the transformer, suggesting that protective devices are working to prevent further damage. The simultaneous line ground fault complicates the situation, as it could lead to cascading failures and affect the stability of the grid if not handled properly. Therefore, this situation necessitates a thorough investigation and the formulation of a corrective action plan to ensure that the issues are resolved effectively and to implement preventive measures against future occurrences.

In contrast, situations like replacing outdated equipment, routine maintenance of transformers, and annual system audits do not generally signify immediate, critical risks to system reliability that would warrant the submission of a corrective action plan to a Regional Reliability Organization. These activities are part of regular operations and maintenance or compliance measures rather than responses to emergent reliability issues.