A briefing by MISO staff last week on the record uplift in the RTO’s energy market caused by Hurricane Laura left stakeholders with more questions than answers.

During a joint meeting of the MISO Markets and Reliability subcommittees, staff recounted the events of Aug. 27, when the Category 4 hurricane made landfall in Louisiana, just east of the state’s border with Texas, damaging about 120 transmission lines and leaving about 730,000 customers in the area without power. (See MISO Keeps Advisories in Effect a Week After Laura.)

The storm caused a unique situation that resulted in nearly $90 million in uplift payments, a record high for the RTO. Though Laura itself barely touched MISO’s Texas footprint — with little rain, wind or even cloud cover, according to the RTO — the hurricane sliced across the West of the Atchafalaya Basin (WOTAB) load pocket, which straddles the Louisiana-Texas border. This created a new load pocket in Texas within WOTAB, which staff variously referred to as the “western load pocket” and the “Hurricane Laura load pocket subarea.”

Only three high-voltage transmission lines were available to serve load in the new pocket because of the storm, and the largest, rated at 500-kV, eventually tripped. This led MISO to direct Entergy to shed about 573 MW of load in the pocket, centered around The Woodlands, about 30 miles north of Houston.

MISO’s Tariff requires emergency pricing for load-shedding events, with each node in the affected area set at the value of lost load (VoLL), $3,500/MWh. But according to staff, the RTO’s pricing software does not allow for an area as small as the new load pocket to be automatically priced at VoLL, requiring staff to spend more than 1,000 hours over two weeks manually entering the prices after-the-fact.

Staff said they were confident that MISO followed the Tariff appropriately, and stakeholders did not dispute that. They did question, however, the rationale for pricing what were presumably “dead buses” in the load-shed area.

Stakeholders also expressed confusion over the different labels for the load pocket, the timeline of events and the map provided by staff. They asked that MISO provide clarifications and a more detailed map that included the nodes that were affected and the three remaining transmission lines.

MISO said it would provide such clarifications at the subcommittees’ meetings next month, and that staff will be prepared to discuss lessons learned and potential policy changes.