Transmission Ratings and Operating Limits Information Exchange (TROLIE)

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Latest Updates

The TROLIE maintainers are pleased to announce that the Real-Time API specification is stable. Read more in the milestone announcement.

If you are new to the project, consider watching the replay of the Intro to TROLIE webinar


With FERC Order 881, North American Transmission Owners, Transmission Operators, Transmission Providers, and Reliability Coordinators must establish a means to exchange ratings information based on current and forecasted ambient conditions. There is no standards body with a mandate to define a technical specification for that exchange and no vendor consortium that is working toward a specification.

TROLIE started as a MISO and GE Vernova collaboration and is now an LF Energy project. Most organizations involved in the operation of the transmission system in North America now need to exchange ratings and related information in an automated, frequent manner. This project will help accelerate their implementation and simplify interoperability.

The project’s specific aims are:

  • In Progress: Define an API specification for the exchange of ratings and ratings-related information to support organizations working to comply with FERC Order 881.

  • TODO: A conformance program to provide vendors a means to demonstrate their compatibility with the above specification and signal their commitment to maintaining compatibility.

  • TODO: An open commons for the development of clients of the API specification.

We are committed establishing a vendor-neutral specification and building an inclusive community.