Research Result Summaries

Leveraging Existing Infrastructure This paper outlines opportunities and challenges faced in efforts to increase the capacity of existing transmission ROWs and introduces approaches to better utilize ROWs. It is based upon the experience EPRI’s transmission team has gained working with individual members to execute increased power flow projects. These studies include the detailed modeling, analysis, laboratory tests, and field implementations needed to evaluate cost, reliability, compatibility, and future maintenance needs.

Reconductoring, Tensioning, and Advanced Conductor Technologies for Increasing the Capacity of Transmission Lines The need and range of options for upgrading the capacity of existing overhead transmission lines or building new high-capacity lines is reviewed in The Electric Power Research Institute’s (EPRI’s) White Paper: Increasing Transmission Capacity on Transmission Lines and Rights-of-Way. The upgrade options discussed in the paper included re-rating, dynamic and ambient adjusted ratings, voltage upgrades and AC to DC conversion. This White Paper provides a more in-depth discussion on conductor technologies and techniques for both increasing the capacity of existing lines or building new high-capacity new lines.

Increasing Transmission Line Capacity Through Ratings There are several low-cost methods to add capacity to overhead transmission lines. These include more accurate calculation of ratings, ambient adjusted or dynamic ratings, and conductor coatings. Traditional overhead lines use static ratings based on assumptions related to worst-case conditions, such as high ambient temperature and low wind speed. When conditions are not the worst case, more current could flow down overhead lines without negative consequences. This white paper provides an overview of how static ratings have traditionally been calculated and describes different approaches for addressing ratings to increase capacity. It also lists the critical considerations and gaps when implementing these approaches and describes ongoing research and field testing presently underway to close these gaps.