ISO-NE announced its plans to increase the transfer limits of three interfaces in Maine at the Planning Advisory Committee’s meeting June 20. 

The RTO is planning to up the limits of the Orrington-South interface from 1,325 MW to 1,650 MW, the Surowiec-South interface from 1,500 to 1,800 MW and the Maine-New Hampshire interface from 1,900 to 2,000 MW.  

Dan Schwarting of ISO-NE said the new limits will be incorporated into day-to-day operations, including the wholesale energy markets, in late June or July. 

“Impacts on capacity transfer limits, and any resulting implications for Forward Capacity Market-related activities, will be discussed in future meetings,” Schwarting said, adding that the new limits will also apply to future planning efforts. 

Asset-condition Projects

New England transmission owners discussed proposals for several major new investments to address degrading transmission infrastructure. 

Zach Logan of Avangrid presented a proposal by Maine Electric Power Co. to replace aging poles on a 345-kV transmission line in the eastern part of the state. While the company has determined “the overall condition of the lines are good to fair, and there are no immediate needs for a complete line rebuild,” most of the poles date back to 1969 and are expected to deteriorate at an increasing rate as they pass 60 years of age. 

The company is proposing to replace structures at a rate of about 40 to 50 per year through 2038, at a total estimated cost of $344 million. 

Chris Soderman of Eversource Energy presented a follow-up to the company’s February presentation of a proposed rebuild of a 115-kV line in New Hampshire, projected to cost about $361 million with an in-service date in the fourth quarter of 2026. 

Responding to stakeholder feedback submitted after the February presentation, Eversource analyzed the costs of a partial line rebuild compared to the full rebuild that is currently planned. The company found that partly rebuilding the line would save money in the near term but ultimately increase overall project costs to about $437 million when accounting for subsequent projects that would be needed to replace other aging structures. 

“The bulk of these structures are already 40 years old” and need to be replaced “in a relatively short time frame,” Soderman said. 

Soderman also presented a proposed $5.5 million project to replace 19 structures on a 115-kV line between Maine and New Hampshire, projected to be complete by the end of the year. 

John Babu of Eversource announced a $5 million project to replace eight relays on a 115-kV substation in Harwinton, Conn. Eversource said the manufacturers are no longer producing replacement parts for the relays.