Dynamic Line Rating Activated by PPL Electric Utilities

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Dynamic line rating data began streaming to PJM operators for the first time this month as part of a PPL Electric Utilities project for three transmission lines in northeastern Pennsylvania.

Initiated in 2020 by transmission owner PPL Electric Utilities and facilitated by PJM, PPL Electric Utilities has said it expects the activation of dynamic line rating (DLR) technology to expand capacity and promote market efficiency on three historically congested lines. PPL Electric Utilities estimates that this DLR project can save customers $23 million annually in congestion costs.

Since launching on Oct. 6, forecast and real-time thermal facility rating updates sourced from PPL Electric Utilities’ DLR systems are being leveraged for reliability and markets processes governing the three 230 kV transmission lines: the two-circuit Susquehanna-Harwood path and the Juniata-Cumberland line.

DLR technology installed on these three 230 kV lines coordinates information from evolving weather conditions to adjust the ratings that govern the lines’ capacity. Hot weather, for instance, tends to increase the likelihood that a line will overheat, and therefore diminishes the amount of current it can safely sustain.

Colder weather and wind conditions have the potential to increase ratings on a line. Other key rating inputs, such as wind speed and direction and conductor sag, provide a view into the potential or actual conductor condition.

Through these measured data parameters about current conditions, performed closer in time to the use of the ratings, DLR ensures reliable operations to protect the DLR facilities and transmission system while reducing overall congestion and promoting market efficiency.

Real-time information about DLRs and the DLRs’ forecasts can be found on the Ratings Information page at PJM.com.

FERC Mandate

As part of Federal Energy Regulatory Commission (FERC) Order 881 issued in December 2021, regional transmission organizations and independent system operators (RTOs and ISOs) are required to establish and maintain systems and procedures to accommodate Transmission Owner projects to implement DLR technology.

PJM’s work to date suggests that transmission technology such as DLRs may lead to more accurate real-time ratings and reduce congestion overall. In comments to FERC, PJM has emphasized that DLR technology is not appropriate for reliability-based projects that are part of PJM’s Regional Transmission Expansion Plan and is not a substitute for upgrades.

Stakeholder Collaboration

PJM and its stakeholders implemented manual changes to enable the PPL Electric Utilities DLR project to move forward. As work continues to facilitate DLR integration within PJM at the direction of FERC, the Dynamic Line Ratings Task Force began work Sept. 30. This stakeholder work effort aims to explore and expand stakeholder considerations related to DLR implementation, markets and planning, including impacts to the Auction Revenue Rights Market, the Financial Transmission Rights Market and seasonal line ratings.