Transmission congestion around New York City could increase after the first 6,000 MW of offshore wind is interconnected without coordinated planning, NYISO told state officials Friday.

The state hopes to develop 9,000 MW of offshore wind (OSW) by 2035.

Having offshore wind energy interconnect to load centers in the city and on Long Island “certainly helps offset some of the transmission constraints that you might experience; but nevertheless, to meet a total 9,000-MW goal of offshore wind, there absolutely will be transmission constraints,” said NYISO Vice President for System and Resource Planning Zach Smith at a technical conference hosted by the state’s Department of Public Service and the New York State Energy Research and Development Authority (NYSERDA).

The conference was intended to inform a study to be completed by year-end on an investment plan to be established by the Public Service Commission for distribution and local transmission upgrades and a second plan for bulk system transmission investments (Case No. 20-E-0197). (See NYPSC Launches Grid Study, Extends Solar Funding.)

Offshore wind is central to compliance with the Climate Leadership and Community Protection Act (CLCPA, A8429), which mandates that 70% of electric power in New York come from renewable resources by 2030 and that electricity generation be 100% carbon-free by 2040.

Smith noted that in the 2019 Congestion Assessment and Resource Integration Study (CARIS), published in July, the ISO only modeled 6,000 MW of OSW for the 70%-by-2030 scenario. As generation increases up to 9,000 MW, transmission constraints around the city and Long Island will worsen, he said. (See Bulk Tx, 115-kV Upgrades Needed for NY 70×30 Goal.)

“There could even be a tipping point, where as you increase beyond that 6,000 MW, it could get much worse than what we’ve identified,” Smith said. “We assumed projects be interconnected according to what’s been proposed in the NYISO interconnection queue. [It’s possible] projects might interconnect much differently than what we assumed in our study, and if they do, then the results will change.

“We believe in general that our results are valid in terms of being indicative of constraints, but when you really dive into the details … those individual transmission constraints really are driven by some of the assumptions on points of interconnection, and that is particularly true with regard to offshore wind,” he said.

HVDC Gains Favor

Technology providers and independent transmission developers also presented the conference with their ideas on how New York’s grid could evolve, including the prospect of more high-voltage direct current (HVDC).

Ben Marshall of the National HVDC Centre in Scotland said the capacity of HVDC in Great Britain will grow from 8 GW today to an estimated 45 GW by 2028 and is expanding in other parts of Europe as well, especially in conjunction with offshore wind interconnections.

Electronic devices that measure the system and take actions increasingly dictate the performance of the grid, Marshall said. Decisions around constraints operate across seconds, decisions around frequency operate across second- to half-second periods and decisions around voltage control are made across hundreds of milliseconds, Marshall said.

“Control systems are making decisions within tens of microseconds; they’re operating very quickly, very flexibly, and it’s important that they operate correctly,” he said.

Marshall also pointed to the emerging risks of having system controls be digital rather than analog: “If I look under the hood of an older car, I know what I’m seeing with the carburetor, but in a new one, all I see is plastic … which is similar to what’s going on with the proprietary control systems, so you need either to counter that effect or to contain it.”

Elizabeth Griffin of Con Edison Transmission said DC technology will be a critical tool to maximize the state’s transmission investments.

“Based on currently proposed projects, it appears that DC will be the future for projects to bring renewables downstate via a potential Tier IV REC [renewable energy credit] procurement, as well for the upcoming offshore wind procurements, just given the distance of the current leaseholds from potential interconnection points,” Griffin said.

DC also has several advantages over AC that make it particularly well-suited for New York’s emerging transmission needs. “DC allows for the maximum utilization of transmission capacity – in the same right of way you can flow more power over DC – as well as for a level of control that is not available on AC lines,” she said. “DC also allows for long distance underground and underwater transmission options that we think will help improve community acceptance by avoiding the need to install additional transmission towers.”

Regulators need to determine how to manage transmission, and particularly how NYISO will operate intrastate DC lines that are integrated with the existing New York Control Area network to maximize its advantages, Griffin said.

Shared infrastructure can maximize the benefits and minimize the environmental impacts of transmission, “which can be particularly beneficial for offshore wind and for aggregating renewables to bring them into New York City,” Griffin said. “Unfortunately, the substations themselves, particularly in Zone J, are often very constrained due to limited real estate, limited physical space within the substation and limited electric capacity. When an open bay at a substation is used to connect less than the maximum capacity potential for that substation, the ability to connect additional volumes without physically expanding the substation may be lost.”

Creating access to the existing transmission grid will require significant additional underground transmission infrastructure that would be best developed with expansion in mind and shared among transmission projects, she said.

“Well-planned and coordinated transmission can make sure that these limited interconnection points are used to provide the maximum benefit and capacity to the system,” Griffin said. “A separate offshore grid will be better for customers in terms of grid reliability, flexibility and total cost effectiveness when compared to the individual generator lead-line approach that has been pursued to date and was appropriate for the initial projects.”

Pancaking and Cost Savings

Transmission developer Anbaric Development Partners determined that 1,500 MW of load was typical of 3 a.m. on any Sunday on Long Island and that therefore there will always be more wind than load. So early on, it started to think about where to put this energy.

The company found 23 points of interconnection (POI) in the city and on Long Island, which screening reduced to about a dozen. Some of the POIs were in good locations but needed to be upgraded to increase their injection capability, said Anbaric Partner and Project Manager Howard Kosel.

“We set a criterion of $1 million per megawatt, and we capped it at $50 million, because we had to set the bar somewhere,” Kosel said. “As we started to grow to get to the 9,000 MW, we were [learning about] the impact the particular POI had on the next POI … it became obvious that upgrading POIs required careful sequencing so as to prevent pancaking, whereby the next POI loses transfer capacity … [and] we saw that we could save upgrade costs of $500 million to $1.2 billion.”

Offshore wind’s intermittency will be complemented by solar and wind energy from northern, central and western New York state, where three public policy transmission projects are now underway under FERC Order 1000.

Innovation is a key benefit for those projects, said Lawrence Willick, senior vice president for project development at LS Power Development, which is partnering with the New York Power Authority on a 345-kV transmission project to relieve congestion at the Central East interface.

“In each case, the selected proposal was selected because of the unique technical features,” Willick said. (See NYISO Board Selects 2 AC Public Policy Tx Projects.)

Fernando Gallinas Victoriano, business development manager for Avangrid Networks, said that integrating 9 GW of offshore wind requires “a planned, coordinated approach” for New York City and Long Island.

“The HVDC technology could be used over existing cables and rights of way, or even through new greenfields, in order to facilitate larger transfer capacity in the system, and with lower implementation periods,” Victoriano said. “Incremental transfer capacity with neighboring systems will bring significant reliability benefits to New York.”

Paul Haering, vice president of capital investments at NY Transco, said that technology and innovation will be critical to achieving the state’s clean energy goals, and that the long time it takes to build transmission “is why we need to act quickly.”

NY Transco was created to develop and own high-voltage electric transmission facilities in New York, and comprises the transmission subsidiaries of Avangrid, Con Edison, National Grid and Central Hudson Electric and Gas.