Transmission Line Rating, Re-rating, and Upgrading, a Utility Perspective Experiences at Public Service Company of New Mexico (PNM)

摘要

Like many electrical utilities, Public Service Company of New Mexico (PNM) is faced with the issue of maximizing the use of existing transmission facilities. PNM owns and operates over 2,500 miles of transmission line located throughout the state of New Mexico. Many of these facilities were built in the time frame from the mid-1950's to the early 1970's. The lines were designed to standards current at the time of construction and to meet the long term system planning requirements projected at that time. These lines continue to be an integral part of PNM's system. Their lifespan has exceeded the planning horizon and the need for transmission of power has increased. In an on-going program that has now spanned over fifteen years, PNM has upgraded over a thousand miles of its 115kV, 230kV, and 345kV transmission lines. This paper addresses PNM's line rating and upgrade program including the establishment of utility line rating standards, analysis of existing field conditions, techniques for mitigating sag limited spans, and examples of typical projects.