An Ambient Assisted Finite Element Approach for DLR Evaluation of Transmission Lines Based on FERC Order 881

The ever increasing demand of electrical energy throughout the world has inevitably caused replacement of generation and distribution components. The replacement of high voltage overhead transmission lines is the most difficult, time taking and costly process due to which sufficient effort is put to avoid their replacement. So their capacity analysis is considered a vital task whenever a system upgrade call is approved and maximum possibilities of running them without replacement are explored. Such capacity analysis involves the thermal modeling of conductor cross section in various ambient conditions of temperature, humidity, irradiance and wind intensity. This paper proposes thermal analysis of an overhead high voltage transmission line using finite element method (FEM) aiming at evaluating the ampacity under different ambient conditions. The effect of all four environmental conditions is applied one by one keeping the others constant to subsequently plot the line resistance and ampacity. As a result, new dynamic line rating (DLR) is calculated for each case and plotted along with the static line rating (SLR) for a fair comparison. It is concluded that the DLR is substantially higher than the SLR which is constant as given on the datasheet and is designed based on the worst environmental conditions.