Grid United Overview
Grid United, a transmission development company, is leading the charge for applying concepts of resource adequacy, reliability, and financial value of interregional high-voltage DC (HVDC) transmission lines to the grid. This is especially true for projects such as North Plains Connector (NPC), a jointly developed project with the energy supplier ALLETE.
Figure 1: North Plains Connector Map. Project route is under development and subject to change. Source: Grid United
North Plains Connector is a bidirectional, 3,000 MW HVDC transmission line connecting the east and west grids of the U.S. between North Dakota and Montana. The more than 400-mile line connects diverse regions with different generation resources and load profiles, harnessing this diversity to improve reliability and optimize resource build-outs.
Grid United approaches development from a landowner first perspective, having already acquired over 90% of the right-of-way needed to construct the project. The North Plains Connector HVDC line is a core part of the North Plains Connector Interregional Innovation (NPCII), a project that the U.S. Department of Energy selected as a recipient for a $700 million grant from its Grid Resilience and Innovation Partnership program. NPCII was selected for the grant due to its interregional benefits which will enhance grid reliability and resilience.
On October 25, Grid United and the DOE kicked off the NEPA (National Environmental Policy Act) process, an estimated two-year process to determine environmental impacts of the new transmission line, and is currently in its scoping phase.
Interregional Transmission Aids Reliability
Electricity and its transmission are sometimes hard to conceptualize because they are something that every person uses, yet very few people think about … until the lights go out. Utilities traditionally take a conservative approach to their operations because their entire role is to keep the lights on, so their business and operational risk is low. However, by narrowing their focus to their local region and transmission network, they may miss solutions available outside of their region.
Interregional transmission can increase reliability by linking diverse resources that improve grid operations and reduce loss-of-load expectation (LoLE). Interregional transmission also supports a reduced reserve margin, reduces the impact of load and renewable forecast errors, reduces the cost and impact of extreme weather, and allows for import or export of power based on the needs of the system.
Grid United commissioned Astrapé Consulting to conduct a reliability study to determine the capacity and reliability value provided by the North Plains Connector under an industry-standard 1-day-in-10-years loss-of-load framework. After calibrating each region to a 0.1 LoLE and adding the North Plains Connector to the model, the change in LoLE represents the reliability that the project adds to the system. By recalibrating each system back up to the 0.1 LoLE standard by adding around-the-clock load to the model, the effective load carrying capability (ELCC) of the North Plains Connector can be calculated similar to how it would be for any in-region generating unit (Figure 2). In this case, the model found that the 3,000 MW bidirectional line contributed over 3,500 MW of ELCC, split between the eastern and western grids (Figure 3).
Figure 2: LoLE Results for the North Plains Connector (NPC) for the Western Electricity Coordinating Council (West) and for the Midcontinent Independent System Operator and Southwest Power Pool (East). Source: Grid United
Figure 3: North Plains Connector (NPC) Capacity Value Because of LoLE Reductions. Source: Grid United
Extreme Weather Risk with Heat Dome in the West (September 2022) and Pacific Northwest Winter Storm (January 2024)
Forecasting is heavily used for modeling the value of new resources on the grid. However, historical data is critical for understanding the real impacts of the resource with realistic volatility. This is true for both seasonal and discrete event risk.
For example, historically, the Midcontinent Independent System Operator (MISO) is a summer risk system and the Western Electricity Coordinating Council (WECC) in the Pacific Northwest (PNW) is a winter risk system, resulting in a logical pairing for connecting with interregional transmission. See Figures 4 and 5.
Figure 4: WECC Percentage of Total Curtailed Load Occurring During Hours of Each Month Across All Model Runs. Source: Grid United
Figure 5: MISO Percentage of Total Curtailed Load Occurring During Hours of Each Month Across All Model Runs. Source: Grid United
Beyond looking at the average trends of each system, discrete events can be analyzed to look at the differences in pricing across the three regions and how the grid responds to stress from such events. To show both a hot and cold weather scenario, Figures 6 and 7 show the price differences during the September 2022 heat dome in the West and the January 2024 Winter Storm in the Pacific Northwest.
Figure 6: September 2022 Heat Wave Pricing Comparison Across Regions. Source: Grid United
Figure 7: January 2024 Winter Storm Pricing Comparison Across Regions. Source: Grid United
In both cases, the extreme weather led to capacity shortages and price spikes. Had the North Plains Connector HVDC line been operational, the Pacific Northwest could have imported power to improve grid stability and increase power availability.
Market Challenges for Interregional Transmission
Currently, there are five back-to-back DC ties between the eastern and western interconnections that are all limited in both size and flexibility. New projects like the North Plains Connector, with modern technology and significant scale, provide the impetus to reevaluate how regions view their neighbors operationally and for reliability.
Although there has been laudable focus on intraregional transmission in recent years, interregional transmission also brings considerable value, which market rules and transmission planning paradigms typically do not capture. In the planning sphere, recognizing the reliability attributes provided by interregional transmission is a necessary first step to incentivizing its development. To capture that value in operations, markets need to better interface with each other to take advantage of the flexibility of which new interregional transmission—particularly HVDC—is capable.
Creating truly all-of-the-above resource adequacy frameworks would help set the stage for further integration of interregional transmission into planning and operations. Probabilistic resource adequacy modeling shows that transmission both adds reliability and can be quantified in the same way as any other resource. With this recognition in hand, transmission owners and independent developers would be more apt to embark on projects, knowing that they would be rewarded for the value they provide.
Michael Skelly
CEO
Grid United
Rachel Broderick
Senior Associate, Commercial Analytics
Grid United
Very informative and educational. I think The North Plains Connector is a game-changer for grid reliability, linking diverse resources across regions to boost resilience and efficiency. Grid United’s landowner-focused approach and progress underline the importance of interregional transmission in securing a flexible, reliable energy future.