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PECO recently completed the installation of a second transmission line to serve its Clay Substation, located in a remote section of rural Chester County, Pennsylvania, U.S. The goal of this work was to improve overall system capacity and reliability for the area. The work required a 25-day outage that completely shut down the existing transmission line to Clay Substation. De-energizing the transmission did not impact the customers as PECO was able to reroute more than 50 distribution circuits serving 35,000 customers so that they did not lose service when the Jennersville Substation was de-energized.
Preparations for the Project
As with any large engineering project, PECO's Clay project required a significant amount of engineering and design work to ensure electric customers would not be impacted adversely by this work. The construction project schedule called for substation outages to last for nearly one month, so short-term solutions would not be adequate. PECO's capacity planning engineers built detailed system models in the utility's CYME Power Engineering application to identify any local problems, such as abnormal or out-of-tariff voltages, cogeneration impacts, fault current contributions and phase-balancing issues. While CYME has been used extensively at PECO, this was the first time it had undertaken such a comprehensive model as part of a single effort.
The initial analysis results recommended several phase-balancing opportunities as well as capacitor installations. It also indicated PECO would need to install temporary generation to provide voltage support for key areas. The focus of the analysis team then shifted to determine strategic locations for temporary generation and the amount needed.
Ultimately, the team targeted four locations for temporary generation. PECO prepared the proposed sites for use by building new terminal poles and modifying the protective relaying schemas to account for the new voltage sources.
AMI Role
Meanwhile, as that work was underway, PECO also was actively deploying its Smart Grid Greater Philadelphia project, which includes a systemwide communications network and new advanced metering infrastructure (AMI). By design, the communications network had already been installed in the Clay Substation area. The communications infrastructure included the installation of fiber-optic synchronous optical networking (SONET) communications rings, WiMAX wireless broadband communications for remote data backhaul, and the Sensus FlexNet network for direct meter communication and distribution automation (DA) devices. The AMI...