Investor-owned utility representatives told New York state officials Thursday that they largely agree with state suggestions on ways to improve their companies’ methodologies for calculating transmission headroom in the state’s effort to accommodate the coming surge in renewable generation (Case No. 20-E-0197).

The utilities outlined their methodology in a November 2020 report, which the state considered in a study released by the New York State Energy Research and Development Authority (NYSERDA) and the state’s Department of Public Service in January.

DPS staff responded in March with a straw proposal for improvements to the headroom calculations, including: employing unified planning data and models; assessing local transmission capacity headroom for onramp needs; and assessing the local amount of additional renewable generation that can be supported without curtailment by the existing grid and incrementally after an upgrade project is placed into service.

“We support the straw proposal because it calls for consistency between the utilities while it recognizes regional differences. It provides the flexibility to adjust the different topologies and design standards of each system,” Martin Paszek, section manager responsible for the design of Consolidated Edison’s transmission system, said at a technical conference held by the New York Public Service Commission.

“The state transmission system, mostly an overhead one, is much, much different from that of the mostly underground, very congested downstate New York City system,” Paszek said. “The consistency will start from the use of the powerful models that the utilities develop on an annual basis with the NYISO. Utilities can then work with DPS and NYSERDA on adjustments of these models to account for the Climate Leadership and Community Protection Act goals.”

“Flexibility will come from the proposed calculation for onramps, where we can get renewable energy onto that 345-kV system — the highway — and offramps downstate, where that renewable energy will be transferred from the bulk 345-kV down to the 138-kV and below,” Paszek said. “We see this straw proposal as a standard for headroom calculations helping guide developers to unconstrained areas of the system.”

All Together Now

The biggest part of the effort is coming up with common assumptions and methodologies to use across the state so that transmission owners or distribution owners do not do the calculations differently or use different assumptions, said John Borchert, senior director of energy policy and transmission development for Central Hudson Gas and Electric.

“The more that we can make sure the approaches are consistent, and the assumptions are done well — how the resources are sited, how they’re moved down from high-level loads down into the system — all of these benefit coming up with a statewide approach,” Borchert said.

Johannes Pfeifenberger, a partner at The Brattle Group, which helped conduct the study, said that one benefit of the state’s proposal is that there are several areas where one utility’s load pocket is dependent on a neighboring utility’s generation facilities, so by having a consistent power flow, planners would also capture the interactions where one facility might limit loads from two different utilities’ generation pockets.

“Capturing those interdependencies is very important because headroom may not be there if it has to be shared,” Pfeifenberger said.

Avangrid also supports the proposed methodologies and the associated benefits, said Paul Didsayabutra, the company’s senior director of networks transmission planning.

How can the process ensure that the utilities all start from the same database or set of databases? asked panel moderator Elizabeth Grisaru of DPS.

“It is critical for this type of calculation, in terms of implementation, that we need to be based on the same starting point, so that seems to be the key part for us,” Didsayabutra said. “There should be some coordination from a working group being formed to work together.”

Borchert said he believes “the base data is consistent, and what becomes more important is how that base case data on a high level is then brought down into the other systems, local transmission and/or distribution, that you’re trying to study. More important than making sure that we’re all starting with the same data and database is how you treat that data as you continue through the study.”

Useful, with Cautions

Pfeifenberger said that while NYSERDA relied on data in the interconnection queue, a lot of those projects never get built, and that the agency’s renewables procurements data could be used to locate the places where transmission will be more needed.

“This assessment should provide a good theoretical feel of locations that have the capability to accommodate renewable energy, so of course developers are going to appreciate that and find it useful,” said Nicholas Culpepper, PSEG Long Island manager of transmission planning. “I think it’s extremely prudent to caveat and be clear with what the results represent, though. … There’s a misconception that these kinds of analyses can be the end-all, be-all.”

The results are based on assumptions that aren’t necessarily going to align with what comes to fruition, and will therefore be subject to change, he said.

“The results should be referenced in concert with other considerations,” Culpepper said. “To list a couple of those: the NYISO interconnection queue; fiscal feasibility; constraints which vary across the different utilities; real estate limitations; and even ease of permitting.”

Paszek agreed and emphasized that downstate real estate is “where you have physical limitations on the feasibility of connecting resources on the system. This analysis provides electrical headroom, but the developers must understand that it’s an ever changing system, and one has to deal with the physical feasibility of connecting.”

What can be most useful is identifying potential substation projects so that areas more likely to develop renewables can have the facilities to do so, Borchert said.

“We all recognize that it’s the question of where are the areas for potential cost-effective renewables development because of the time it takes to develop projects,” Grisaru said. “In addition to asking NYSERDA’s help, what can developers do to help the planners narrow down those areas of investment?”

As to whether there is a value to expanding existing models to include distribution, Borchert said there are models such as hosting capacity maps that do a lot with headroom calculations and portrayal of headroom.

“I think what is being proposed here may be a bridge too far,” Borchert said. “Some of the existing models, like Con Ed’s system where it goes down and feeds the area substations, it’s appropriate to have the models down to that level because there’s a need to go beyond the sub-transmission into distribution because that area is networked.”

Borchert said he did not see the value of analyzing the bulk system down to the individual customer load model in order to assess how much new transmission or upgrades would be needed to bring more renewable energy onto the grid.

Culpepper agreed and said that modeling distribution with transmission would involve heavy work with “minimal to no value” for his service territory on Long Island.