By Amanda Durish Cook

MISO planners are considering a study on the benefits of expanding flows on the constrained transmission interface linking the RTO’s North/Central and South regions, including the option of building its own additional transmission.

Dubbed the Footprint Diversity Study, the proposed initiative would look beyond just the impact of increased energy flows at the interface to examine the “widespread” economic factors related to expanding the North-South tie, such as system-wide capacity benefits, settlement cost savings and savings in adjusted production costs when flows exceed settlement limits.

“There’s going to be multi-value associated with such a line and it needs to be looked at from all aspects,” MISO Director of Policy Studies J.T. Smith said at a March 16 Planning Advisory Committee meeting.

Smith said the study would also consider the economic implications of the flow limits in the settlement agreement allowing MISO to use a portion of SPP’s system to facilitate transfers with Entergy’s former service territory. MISO estimates the system’s actual transfer capability is greater than current market flow limits, which restrict southbound flows across SPP’s network to 3,000 MW while capping northbound flows at 2,500 MW.

Depending on usage levels at the interface, use of SPP’s network can cost MISO up to $38 million per year, according to the RTO.

Smith said MISO would specifically examine the feasibility of building its own transmission to handle increased transfers between the sub-regions.

If the study is greenlit, MISO will rely on its 2017 Transmission Expansion Plan to inform any proposals to develop a new line. Smith also noted that future changes to MISO’s market efficiency project rules could influence a potential project.

“We also need to consider that the rules that exist today may not be the rules that exist tomorrow,” he said.

Consultant Roberto Paliza of Indianapolis said he was concerned that MTEP 17 would come too late to address increasing North-South tie flows. MISO shouldn’t assume SPP will provide the same amount of capacity after 2021, when the settlement agreement expires, he added.

“I wonder whether there’s going to be enough time to build the transmission to handle the capacity contract path,” Paliza said. “I wonder if we need to do something sooner than doing something at the overlay transmission stage of the MTEP 17.”

Paliza said he views the SPP-MISO settlement as a temporary fix for a problem that requires a long-term solution.

Minnesota Public Utilities Commission staff member Hwikwon Ham said he “didn’t necessarily disapprove of [the potential North-South] project” but noted it would involve a hefty price and wanted to know if MISO had explored possible cost allocations.

Smith said it was too early to identify such allocations, but that the issue would be taken up with the Regional Expansion Criteria and Benefits Task Force if a project is identified.

Smith did not provide a deadline for getting stakeholder approval for the study or a possible start date.