Outage impact on AEP-MECS interface; April 2009

February 16, 2009

AEP Cook Transformer Outage Information

This notification is to provide information on the impact of a transmission outage, in addition to other expected system conditions, on the AEP-MECS interface in April 2009. Starting on April 1 2009, AEP will be taking an outage of the Cook 765/345 kV transformer and the Cook 345 kV bus for an upgrade under PJM eDart #233128. The bus outage sets up a potential contingency where the loss of the Cook-Benton Harbor 345 kV line will also remove the Cook-Palisades 345 kV from service. The outage was jointly studied by PJM and MISO for reliability and for determining the power transfer capability through the AEP-MECS interface.

The study concluded that due to first contingency thermal or voltage violation criteria, the power transfer through the AEP-MECS interface may be restricted to approximately 2200 MW. To maintain reliability, the flow on the AEP-MECS interface and on the Argenta-Twin Branch 345 kV tie line will be limited in order to not exceed first contingency thermal or voltage limits for the duration of the outage. In addition, the study identified critical generators and necessary capacity in the region to facilitate the outage.

PJM and MISO Planning & Operations will continue to assess other planned and unplanned outages in the region for impact.