Transmission expansion planning model considering conductor thermal dynamics and high temperature low sag conductors

The means for transporting more power through an existing transmission corridor have been given considerable attention in recent studies. Reconductoring a path with a conductor that has a higher thermal capacity, such as a high temperature low sag (HTLS) conductor, is one possible option with minimal structural modification and out-of-service time. Parallel line additions or HTLS parallel line additions are other options that can increase transfer capabilities and reduce operating costs. Thermal constraint relaxation is another option, which is an operational based method that allows the line flow to exceed the steady-state line rating for a certain penalty price. Since such operation may deteriorate the expected service time of the conductor, the penalty price should be determined properly. In this study, the above options are captured to create the proposed transmission expansion planning model. In addition, a conductor degradation model is introduced to capture the associated degradation costs due to operating conductors at elevated temperatures. Numerical simulations conducted on the IEEE-24 and IEEE-118 bus system indicate the effectiveness of the proposed approach to increase system capacity while preserving current right-of-ways (ROWs).