Regional System Plan Updates
The ISO-NE Planning Advisory Committee on Wednesday received a project list update for the Regional System Plan (RSP) from Rudi Vega, the RTO’s principal engineer for transmission planning, that included 12 new projects to resolve thermal overloads and voltage violations in New Hampshire and Maine.
Eight of the projects are for Maine and involve rebuilding 21.7 miles of an existing 115-kV line with additional work on MVAR synchronous condensers, capacitors and reactors. The total cost across all projects is $158.6 million.
The other four projects, in New Hampshire, will cost a total of $134.9 million. They also involve the installation of MVAR synchronous condensers and capacitors, in addition to 115-kV and 345-kV breakers.
ISO-NE also informed the PAC that it had changed the cost estimates for two projects since the previous list in June: an increase of $7.1 million for the Southeast Massachusetts/Rhode Island Reliability Project (SEMA/RI), based on a transmission cost allocation application submitted in August; and a reduction of $8 million for the Greater Boston Project.
Three projects have been canceled since the June update, as they are no longer needed because of the New Hampshire and Maine solutions:
- a new, $62.7 million 115-kV line section and upgraded section between Coopers Mills and Highland substations at the Maine Mid-Coast Spur;
- adding a second 115/345-kV autotransformer at the existing 115-kV Kimball Road substation in Maine, along with moving one of the 115-kV/30-MVAR capacitor banks, which would have cost $3.3 million; and
- installing a transfer trip at Kimball Road to disconnect the town of Lovell, Maine, from 115 kV for an estimated $0.5 million.
Eversource Details Phase II of Wood Structure Replacement Program
Eversource Energy (NYSE:ES) will replace 241 laminated wood structures across five 115-kV transmission lines in New Hampshire and one 345-kV line in Connecticut with weathering steel monopoles, installation of lightning arrestors and counterpoise grounding, according to a presentation from the utility.
According to Eversource’s Dave Burnham, the new monopoles would allow the utility to comply with current clearance and strength code requirements, improve reliability and storm resilience, and support larger conductor sizes if needed in the future.
Burnham also said recent cross-sectional inspections of removed wood structures uncovered significant damage not detected in previous, visual inspections, such as:
- rot present throughout the length;
- open joints at the top, allowing free entry of water;
- damp wood at the center, soft with rot;
- voids between layers of varying size and location, but present on each cross-sectional cut; and
- additional splitting behind surface cracks.
Replacements performed since March have continued to uncover structural damage. (See “Eversource Replacing Wood Structures in NH,” ISO-NE Planning Advisory Committee Meeting Briefs: March 17, 2021.) Eversource says it will coordinate replacement schedules with ongoing projects to maximize mobilization, permitting and outreach efforts, and shared right-of-way access.
The current work addresses priority lines at the cost of $55.6 million, with in-service dates ranging from the first quarter of 2022 to the first quarter of 2023, Eversource said. Additional structures removed during these projects will continue to be assessed for internal damage. The utility will assess the remaining lines with laminated wood structures in the coming months, and additional replacement projects will be presented to the PAC in 2022 for Phase III.