161-kV and 500-kV Transmission Line Thermal Analysis

Location: Chattanooga, Tenn.

Client: Tennessee Valley Authority

Burns & McDonnell has worked with TVA to complete the modeling and analysis of approximately 1,000 miles of 161-kV and 500-kV transmission lines on its grid. TVA hired Burns & McDonnell to model and analyze a select group of 161-kV and 500-kV lines that were targeted for operation at 100 degrees Celsius.

Due to the large number of lines and mileage represented in this select group, and due to an accelerated work schedule, TVA coordinated the teaming of an aerial laser surveying company to work with Burns & McDonnell to accomplish the work in a short time. The aerial surveying used helicopters and fixed-wing aircraft in tandem with ground surveying. Survey data was collected from a helicopter-mounted laser that scans perpendicular to the flight line. The fixed-wing aircraft provided aerial photography, including still photos, of the transmission corridor. The survey data was then used by Burns & McDonnell engineers to create a three-dimensional model of the line in PLS-CADD, a transmission line modeling and engineering software package. The complete model was then analyzed at the requested operating temperatures of 70, 80, 90 and 100 degrees Celsius. The transmission lines were then checked for clearance violations at these temperatures using National Electric Safety Code and TVA clearance requirements.

Additionally, Burns & McDonnell developed construction costs and recommendations using TVA-established criteria for each of the requested operating temperatures. A complete report, including plan and profile drawings, violation drawings, clearance reports, structure coordinates to be used for GIS purposes, estimated costs, and recommendations, was delivered to TVA for each and every transmission line analyzed.