345–138 kV substation upgrade project

A primary goal of electric utilities is to maintain reliable and stable service. Therefore utilities forecast and evaluate future power system scenarios and implement the necessary improvements to mitigate adverse impacts. The reliability and age of the existing substation in their northeastern service territory prompted Commonwealth Edison Company (ComEd) to initiate a major substation project. To support reliability and reinforcement improvements to their 138 kV system, a plan was developed to provide an additional source of power into the 138 kV system from the 345 kV system. This involved bisecting an existing 345 kV transmission line and constructing a new 345 kV to 138 kV substation. This paper summarizes engineering solutions to the many challenges involved in a complex transition from old to new facilities. The project was completed with no adverse events and met the stated project objectives.