Providing On-Site Generation Options for a Utility

Gresham Smith is assisting Holston Electric Cooperative (HEC) with engineering services in association with the installation of a 4.3/4.5 Megawatt (MW) methane-ethane dual fuel interconnection with Tennessee Valley Authority (TVA). This generation system will be configured with 1.5 mega-volt amperes (MVA) connected to HEC’s Bulls Gap 161/13kV substation, and 3.01MVA connected to HEC’s Persia delivery point. The purpose of this project is to help provide some load-shed opportunities for the utility at the two substation locations by allowing a portion of the load to be maintained from the generators which will reduce that portion of load from being maintained at the substation facilities.

Our Energy & Utility Infrastructure team is providing a variety of engineering services for the project, including assisting with the interconnection between the generator packaged units and the pad-mounted transformers to the distribution feeder connections. The three-phase pad-mounted transformers are being fed on the secondary side by the generators, and the primary side is connected to HEC’s Bulls Gap and Persia substations. In addition, Gresham Smith’s team conducted an analysis of the applicable settings for all protective devices involved, so that if a fault occurred on HEC’s system, the generator’s main breaker will operate before the protective device or recloser operated, which will prevent a “hard shutdown” of the generator as to avoid damage to the equipment.