The acronyms stand for Transmission Service Agreement and Federal Energy Regulatory Commission. The filing is a key step for the project.
The TSA was filed December 15 and basically sets out the rules of the road for the use of the transmission line once it is in service. The FERC must approve the agreement in order for the project to move forward.
There’s a lot of material available, including a press release, here, and the full (703 pages!) filing, here. One item of interest within the large filing is a report by Charles River Associates that focuses on the impact Northern Pass will have on regional energy prices in New England. An excerpt:
“…the additional capacity that will be provided by NPT will reduce congestion by allowing more power to be delivered during the hours when prices are highest and to the market where the power is valued most. The result of the congestion relief will be lower ISO-NE prices, lower fossil-fueled generation in New England, reduced production costs, and lower costs of wholesale power purchased through the New England market…”
(page 672 of the .pdf; page 18 of the CRA report. Page 651 of the full .pdf marks the beginning of the CRA report.)