As most transmission grid owners and operators know, FERC has issued an Advance Notice of Proposed Rulemaking (ANOPR) about potential reforms requiring Dynamic Line Ratings (DLR) and enhanced reporting practices on transmission lines. FERC’s stated goal is to reduce congestion costs, facilitate new resource interconnection, and improve reliability through broader deployment of DLR.
In the months since FERC issued the ANOPR, industry watchers and operators have responded candidly about the benefits and potential roadblocks to broad-based deployment of DLR. We fully support FERC’s objectives and recognize DLR’s critical role in revealing grid capacity and accelerating interconnection of more reliable, inexpensive renewable energy sources. These potential reforms will enhance data reporting capabilities and practices and provide transparency that is sorely needed by utilities as they optimize grid resources. What’s more, using the maximum capacity of grid resources enables the interconnection and distribution of less expensive renewable energy – saving consumers billions.
According to a WATT Coalition congestion report issued just this month, “...insufficient transmission grid capacity blocks the delivery of lowest-cost power to consumers. Measured through grid congestion in “organized markets” where congestion is transparently reported, total congestion costs in 2023 amounted to $8 billion. Scaled based on electricity demand, that number implies $11.5 billion in congestion costs nationwide in 2023.”
Some operators are already seeing results from DLR. Our customer, PPL Electric Utilities, installed DLR on three of its most congested 230 kV transmission lines in northeastern Pennsylvania in 2022. According to company statements, it expects the activation of dynamic line rating (DLR) technology to expand capacity and promote market efficiency on three historically congested lines. PPL projects that it can save customers $23 million annually in congestion costs.
Why Isn’t FERC Order 881 Enough?
This is where it can get complex. FERC Order 881, which goes into full effect in July 2025, requires that transmission providers use Ambient-Adjusted Ratings (AAR) to identify and report unused transmission capacity. Order 881 is a significant step forward in grid utilization as it puts systems in place to receive and analyze dynamic (rather than static) line ratings. The adoption of AAR is worthy of congratulations to the utilities that have implemented the technology.
But, since it relies on only ambient air temperature calculations, AAR is unable to account for cooling conditions caused by wind. DLR sensors provide more accurate, localized ratings, and often reveal additional transmission capacity because they accurately measure wind. We find that typical capacity gains with AAR are about 5-10% while DLR is often about 20-40%. Of course, each line in the grid is unique and, due primarily to wind conditions, some cannot be improved more than 5%-10% even with DLR.
Lines with the greatest potential for capacity gains can be easily identified with detailed line assessments, helping utilities prioritize AAR and DLR investments. The beauty of these assessments is that they can be done using historic weather data and before installing any equipment or systems – this means that utilities can easily and accurately assess the business case and benefits on a line-by-line basis before committing. Our experience is that the return on investment for installing DLR on congested lines is a matter of weeks, rather than months let alone years!
Summing it up:
Requirements to deploy DLR would go far further than Order 881 to ensure that congestion costs are only incurred with lines that are truly at capacity. Additionally, precise DLR line ratings allow operators to prioritize transmission grid improvements while optimizing the use of existing grid assets. DLR will also accelerate interconnection of cheaper and cleaner generating resources and allow grid infrastructure to adapt to serve changing needs.
Ampacimon, along with other WATT Coalition members, support a broader requirement to deploy DLR across transmission lines beyond the minimum. We agree that DLR can reduce congestion costs, improve reliability and safety, and reduce congestion barriers that prevent the interconnection of new, lower-cost energy sources.
Knowing that deployment of DLR requires long-term planning, we also recognize that AAR is sufficient for non-congested lines, at least in the short time. And that AAR can benefit even the most congested lines, incrementally. The benefits, beyond AAR, of DLR are realized when there is sufficient wind, at the right direction, to cool the lines and therefore identify additional capacity.
While DLR won't reveal hidden capacity on every transmission line, it will provide highly accurate monitoring of each individual line. DLR can reveal lines that can safely carry more power, paving the way for more rapid interconnection.
Both FERC Order 881 and potential new regulations will allow utilities to plan capacity upgrades judiciously and efficiently and utilize existing grid assets to the greatest benefit of consumers, and the environment.
Check out our FERC ANOPR webinars to find out more about this topic.
