By Amanda Durish Cook
FERC on Tuesday approved simultaneous transmission import limits for several balancing authority areas in the Southeast, stretching from Kentucky to Florida.
The 16 simultaneous import limits (SILs) were submitted with non-public market power analyses by several transmission-owning companies, including eight subsidiaries each of Southern Co. and Duke Energy; seven NextEra Energy affiliates (including Florida Power & Light); PPL affiliates Louisville Gas & Electric and Kentucky Utilities; Tampa Electric Co.; and South Carolina Electric & Gas. (ER10-1325–008, et al.).
FERC will use the SIL values to evaluate market power analyses submitted by the region’s transmission owners (TOs) and non-transmission-owning sellers.
The limits range from a 10.7-GW import capability during winter in the Tennessee Valley Authority balancing area down to a zero-megawatt year-round import limit in the Florida Power & Light balancing area. The limits were created based on a study period extending from December 2014 to November 2015.
While FERC accepted most of the transmission owners’ own SILs, it said it selected Tampa Electric’s calculated values for a few Florida balancing areas where various TO SIL values conflicted with one another.
The commission commended the TOs for coordinating to create the SIL values but said in the future SIL calculations must follow a commission-ordered procedure.
“The southeast transmission owners generally performed their SIL studies correctly. However, the review of these filings, as well as the review of filings for other regions, leads the commission to conclude that it is appropriate to remind sellers of its expectations, and provide clarification, with respect to the calculation of SIL values,” FERC said.
FERC said TOs should abide by the tariff-approved methodologies to calculate SIL capability and should take into account voltage and stability limits, capacity benefit margins and transmission reserve margins.
“The commission emphasizes here that each transmission owner’s SIL values must reflect [transmission reserve margins] and [capacity benefit margins] in the same manner as utilized to calculate and post [available transfer capability] and to evaluate requests for firm transmission service,” FERC said.
