FERC accepts SPP interconnection agreement for North Plains HVDC transmission line
- Agreement links North Plains HVDC line to Basin Electric system
- Line to carry approximately 1,500 MW between Montana and North Dakota
- Agreement takes effect Oct 11, 2026
WASHINGTON, Oct 8 — The Federal Energy Regulatory Commission (FERC) on Thursday accepted Southwest Power Pool's (SPP) executed interconnection agreement with North Plains Connector LLC and Basin Electric Power Cooperative. The agreement sets the terms for connecting North Plains' proposed high voltage direct current (HVDC) transmission facilities to Basin Electric's transmission system.
According to the order, North Plains' HVDC transmission facilities will provide approximately 1,500 MW of transfer capability between the Colstrip 500 kV substation in Rosebud County, Montana, and the proposed Junction 345 kV substation in Morton County, North Dakota. Commercial operation is planned for Nov. 30, 2032.
The commission found the agreement "just and reasonable and not unduly discriminatory or preferential." It accepted the agreement with an effective date of Oct. 11, 2026, as SPP requested.
According to the order, the agreement specifies that North Plains must complete HVDC interconnection design studies and any necessary project-specific studies before the commercial operation date.
The agreement provides that, once the studies and any network upgrades are complete, connected generation in either the Eastern Interconnection or the Western Interconnection will be eligible to participate in SPP's Integrated Marketplace, according to the order.
The commission said the agreement's terms are similar to those in other transmission interconnection agreements it has accepted. SPP noted in its filing that its tariff has no pro forma agreement for transmission interconnections.
SPP filed the agreement on Aug. 11, 2026, in Docket No. ER26-3477-000. Basin Electric filed a timely motion to intervene. In July 2025, the commission accepted SPP tariff revisions that set up a separate planning process for evaluating HVDC interconnections.