Richard Kornitsky, ISO-NE assistant engineer for system planning, on Wednesday presented the Planning Advisory Committee with revised study scenarios and threshold prices, as well as other high-level assumptions, for the 2020 Economic Study requested by National Grid.
The utility asked for a study focusing on 2035 to provide stakeholders analyses of the best ways to meet state clean-energy goals cost-effectively, leveraging transmission and storage as needed.
A set of incremental resource scenarios will model two different amounts of offshore wind interconnections, but the substantial focus is on bidirectional use of existing and proposed external tie lines, as well the use of Hydro-Québec as virtual storage, Kornitsky said. Hydro-Québec could provide virtual storage by curtailing its hydro production when New England renewables are overproducing and making resources available when ISO-NE needs them.
In response to a stakeholder question, Kornitsky said that the RTO implemented bidirectionality by incorporating renewable energy credits, recognizing that RECs can allow resources to be profitable even when LMPs are negative.
The study will use bidirectional threshold prices reflecting REC values to first curtail imports, then trigger exports, with renewables curtailed once export capability is exhausted. The prices range from -$100/MWh for behind-the-meter PV to -$30/MWh for onshore wind. The trigger for exports is assumed at -$25/MWh.
Storage Opportunities
Batteries will be a “central focus” of the 2020 Economic Study, Kornitsky said. They will be modeled with a round-trip efficiency of 86% and presumed to respond to LMPs and provide “system capacity,” regulation and reserves.
While ISO-NE Economic Studies do not consider capital costs and fixed operating and maintenance expenses, one stakeholder said such costs and expenses should be “baked in” to the analysis of utility-scale energy storage facilities.
In the third quarter, the RTO will present draft production simulation results, identify sensitivity scenarios and assumptions, and present assumptions for ancillary services analysis. In the fourth quarter, it will present sensitivity scenarios, simulation results and draft ancillary services results before issuing the draft and final reports in the first quarter of 2021.
Two Eversource Projects in Conn.
Eversource Energy engineer Christopher Soderman presented a $13 million project involving circuit separation, structure replacement and reconductoring with optical ground wire (OPGW) of approximately 1 mile of four 115-kV transmission lines crossing Horton Cove in Montville, Conn.
“Reliability is the main driver here,” Soderman said.
Quad-circuit lattice towers and adjacent structures create the potential for disturbances on multiple circuits, while the structure geometry creates small phase-to-ground clearances and an increased probability of faults because of lightning strikes. Soderman said Eversource had 19 disturbances since 2010 caused by lightning strikes or shield wire failures, including three in the last four years in which a single event caused multiple transmission line outages.
The projected in-service date is in the third quarter of 2021.
Soderman also presented a $23 million project to replace 96-year-old double-circuit steel lattice towers between East Granby, Conn., and Agawam, Mass., and to replace old shield wire with OPGW on 7.5 miles, nearly half of the line’s total length.
The project involves replacing 70 decrepit towers with 63 direct-embed, weathering steel monopoles and seven engineered weathering steel monopoles on concrete foundations. Eversource will also install 62 lightning arrestors. The project is estimated to go in service in the fourth quarter of next year.