NYISO researcher outlines market model for a proposed internal controllable HVDC line

Hossein Lotfi, a senior market solutions engineer at the New York Independent System Operator, presented a market modeling approach for an "internal controllable line" (ICL), a proposed HVDC link with both ends inside NYISO's control area intended to move up to about 1,300 megawatts of power between Upstate New York and New York City.

Lotfi said the ICL is proposed to help New York meet the Climate Leadership and Community Protection Act (CLCPA) targets by moving renewable energy southward where demand is concentrated. "The internal controllable line, or ICL, was proposed to alleviate the transmission losses because they incur lower power losses, and they are more economical than the equivalent AC lines at the line distance," he said.

The core of Lotfi's presentation was a generalized location-based marginal pricing (LMP) energy-market model that treats the ICL as an entity that can submit bids in both directions and that explicitly accounts for transmission losses and price spreads between source and sink nodes. Lotfi contrasted that model with existing arrangements: wheeling or point-to-point DC arrangements, which either assume lossless transfers, do not support bid submission, or model constant contracted flows rather than market-optimized schedules.

Lotfi presented a 3-bus test case to show how the model represents bidirectional flow using paired proxy generators and loads and how it represents losses (for example, a 1% loss factor in the test case). He explained bid semantics using a four-quadrant interpretation: positive and negative values for directional bids map to discharge/charge analogies ("equivalent to battery discharge" or "battery charge") and determine whether the ICL operator is paid or pays to schedule flow.

"This will be the first fully controllable HVDC line in The US with both ends in the same control area," Lotfi said, describing the proposal as novel within U.S. grid practice.

On assumptions and limits, Lotfi said the NYISO simulations assumed an ICL loss factor of about 1%, a capacity limit in the study on the order of 1,200'00 MW for the modeled cases, and that ancillary-services and ramping constraints were not modeled because the specific HVDC converter technology is not yet selected. He flagged that these simplifications could change with vendor data or a technology choice.

In Q&A, Lotfi said the study did not analyze reactive power or voltage control and treated the work as an energy-market analysis only; he suggested those topics are suitable for follow-up research. On losses, he said vendor discussions indicated modern HVDC technology could achieve roughly 1—2% losses in the relevant operating range, which the study used as a simplifying assumption.

The presentation is based on a published IEEE Power & Energy Society paper Lotfi referenced; he encouraged attendees to consult the paper for technical detail.

Next step: Lotfi invited follow-up with NYISO staff and the research team for deeper technical inquiries and noted the proposal remains subject to vendor and policy decisions.