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By | June 19, 2024

Open Sustainability Policy Summit Recap and Video: FERC Order 881: Ambient-Adjusted Transmission Line Ratings

The Open Sustainability Policy Summit (OSPS) 2024 recently hosted a session on the Federal Energy Regulatory Commission’s (FERC) Order 881, presented by Tom Dautel, Director of the Division of Economic and Technical Analysis at FERC (video follows below). Here’s a detailed look at the key takeaways from the session, focusing on how this order is set to revolutionize transmission line ratings and address inefficiencies in the power grid.

What is FERC Order 881?

FERC Order 881, issued in 2021, aims to overhaul the calculation of transmission line ratings. Transmission line ratings are crucial as they determine the power flow limits on transmission lines to prevent overheating. Traditionally, these ratings have been static or seasonal, based on worst-case weather conditions anticipated over the lifetime of the line. However, such methods often lead to artificially constrained power flows and, consequently, unjust and unreasonable electricity rates.

The Move to Ambient-Adjusted Ratings (AARs)

Order 881 mandates the use of Ambient-Adjusted Ratings (AARs), which are line ratings updated close to real-time, reflecting short-term forecasts of ambient air temperature. This approach ensures that transmission line ratings are more accurate and dynamic, adjusting to actual weather conditions rather than conservative estimates.

Key Implementation Guidelines

  1. Frequent Updates: Under Order 881, transmission operations within the next 10 days must utilize AARs. For operations beyond 10 days, at least seasonal ratings based on four seasons must be used. This shift from static to dynamic ratings aims to enhance the accuracy of transmission limits.
  2. Hourly Calculations: Ratings must be updated hourly and calculated up to 10 days in advance. This requirement significantly increases the volume of data to be managed and shared among transmission providers.
  3. Data Sharing: Transmission providers are required to share line rating data in a timely manner upon request. This transparency is essential for efficient grid management and coordination among different providers.

Impact on Power Markets

Transmission line ratings play a pivotal role in both centralized and bilateral wholesale power markets. By ensuring that ratings are more reflective of real-time conditions, Order 881 aims to reduce artificial congestion and enable a more efficient and cost-effective power distribution system. Centralized markets, which operate through computerized auctions, and bilateral markets, where utilities negotiate individual transactions, will both benefit from these more accurate ratings.

Technical Considerations and Challenges

Implementing AARs involves significant technical and practical challenges. Transmission providers need to adopt new forecasting and data management practices, dealing with a substantial increase in data volume. Additionally, there is a need for transmission providers to become comfortable with these new technologies and methodologies.

Looking Ahead

FERC’s move towards more dynamic transmission line ratings through Order 881 is a significant step towards enhancing the efficiency and reliability of the power grid. While the transition poses challenges, the potential benefits in terms of reduced congestion and more accurate electricity pricing make it a crucial development in the quest for a more sustainable energy future.

For those interested in the technical specifics and further details, FERC provides extensive resources and documentation.