I am glad FERC has followed up FERC Order 881 mandating Ambient Adjusted Ratings (AARs), issued December 2021 with this Notice of Inquiry on Dynamic Line Ratings (DLRs). Taken in total AARs and DLRs are part of the Grid Enhancing Technologies.
FERC defines AARs as, “propose to define an ambient-adjusted line rating, or AAR, as a transmission line rating that: (1) applies to a time period of not greater than one hour; (2) reflects an up-to-date forecast of ambient air temperature across the time period to which the rating applies; and (3) is calculated at least each hour, if not more frequently.”
FERC defined[1] Dynamic Line Ratings DLR as "as a transmission line rating that: (1) applies to a time period of not greater than one hour; (2) reflects up-to-date forecasts of inputs such as (but not limited to) ambient air temperature, wind, solar irradiance intensity, transmission line tension, or transmission line sag; and (3) is calculated at least each hour, if not more frequently."
FERC Staff White paper is a good reference for both AARs and DLRs. https://www.ferc.gov/sites/default/files/2020-05/tran-line-ratings.pdf
[1] FERC NOPR on Transmission Line Ratings, eLibrary | File List (ferc.gov)
It remains to be seen how fast transmission providers like transmission owners and independent system operators implement GETs in interconnecting renewable projects because interconnection queues are backlogged by 2-3 years at most grid operators.
In the words of Pine Gate Renewables who submitted these comments in the FERC Advanced Notice of Proposed Rulemaking (ANOPR), this is the issue, “Pine Gate has advocated for GETs to be considered in the interconnection process as a means of reducing the need for costly network upgrades, but is often met by resistance from RTOs/ISOs and transmission owners. In one such case in an eastern RTO/ISO, Pine Gate is developing a solar project that will interconnect to a transmission line on which much of the capacity is currently being used by a thermal generator that has committed to retiring in the near future. The RTO/ISO has determined that the interconnection of the solar project will cause an overload on the transmission line and therefore has allocated to the solar project tens of millions of dollars of network upgrades. However, once the thermal generator retires, the transmission line would no longer be overloaded, thereby eliminating the need for the costly network upgrades. Pine Gate has proposed that the RTO/ISO and transmission owner consider using DLR and Advanced Power Flow Controls as a means maximizing existing capacity on the transmission line and rerouting flows around the potential overload until the thermal generator retires. This would alleviate the need for the costly network upgrades and allow the solar project to come online much faster. Unfortunately, neither the RTO/ISO nor transmission owner has committed to seriously considering GETs as a potential solution.”
On the other hand, MISO says (in the same docket), "it would not be good utility practice to rely on ambient adjusted ratings or dynamic line ratings within the generation interconnection process”.