By Amanda Durish Cook

BRANSON, Mo. — MISO staff and the Independent Market Monitor agreed that the RTO’s markets performed as they should have this spring, but both found a surge in MISO South outages troubling.

MISO reported an average 69.2 GW of load March through May, up 1.3% from 68.3 GW in spring 2016. Executive Director of Strategy Shawn McFarlane said hotter-than-normal spring temperatures contributed to the load increase. The RTO hit a 92.2-GW spring peak on May 16.

The average spring real-time energy price was $29.96/MWh (the Monitor reported an average $29.90/MWh), a 39% increase from spring 2016, driven by a sharp increase in gas prices, MISO said. Market Monitor David Patton said natural gas prices rose 57 to 65% year-over-year, with the highest price spikes in Texas and Louisiana.

McFarlane said the higher load, combined with forced outages, caused high real-time congestion on multiple days, particularly in the South and Central regions.

MISO racked up $467 million in congestion during the quarter, Patton said during his quarterly report delivered on the first day of summer to the Markets Committee of the Board of Directors. He cited higher gas prices as a contributor to the rise in congestion, saying “gas-fired units are often marginal when generation is redispatched to manage network flows.”

“MISO experienced the most congestion of any other RTO in the country … almost half a billion dollars,” Patton said. He repeated his proposal for relieving congestion: that MISO and its neighbors transfer the control of border constraints when one RTO has more relief on a flowgate than the other.

“A good reminder that there is always work to be done at the seams to improve things for our constituents,” Director Paul Bonavia said.

The congestion was also because of high planned outages in MISO South, Patton said, adding that the RTO should seek additional authority to approve and coordinate outages. Expanding the authority of the RTO, which is currently limited to a “reliability review,” will be one of the recommendations in his annual State of the Market Report this month.

Under its Business Practices Manual, MISO can only “recommend [an outage] schedule that maintains system security and minimizes adverse impacts.” Owners and operators submit planned maintenance outage schedules for generators 10 MW and above to MISO for a minimum rolling 24-month period. The RTO studies the impact of all transmission and generator outages and works with owners to reschedule when an “outage analysis indicates unacceptable system conditions” or when a zonal maintenance margin is reached. “We have to not schedule ourselves into emergency situations. The ability to schedule them to minimize their effects will be a significant savings,” Patton said.

There is no need for all resources to schedule their maintenance outages in the spring and fall shoulder months, Patton continued, noting that capacity often exceeds winter load in the South by so much that it becomes “stranded” because of the limit on South-to-North transfers. “Economic opportunities likely exist to shift outages from shoulder to winter months,” he said.

Outages in MISO South removed as much as a 34% share of capacity during the spring, and outages in MISO Midwest took about 25% of capacity. Last year, spring outages took out 15% in the South and 14% in the Midwest. As a consequence, real-time congestion cost increased more than 50% over last winter and the prior spring quarter, according to the Monitor.

Patton also noted that the transmission and generation outages and extreme weather in the South led to 22 days of conservative operations in load pockets and three days with maximum generation alerts in April. An emergency maximum generation event on April 4 was spurred by the loss of a large nuclear unit, apparently Entergy’s Grand Gulf 1 in Mississippi, which the Nuclear Regulatory Commission reported going out of service because of a condensate leak.

Director Baljit Dail asked if there was a reason behind the spate of outages. “It just struck me as a massive increase. … It was two-and-a-half times what we normally have,” he said.

Staff agreed the outages were higher than the usual crop of shoulder-season outages.

“We do agree with Dr. Patton’s suggestion that a higher degree of coordination would be useful,” Chief Operating Officer Richard Doying said.

Bonavia said he once commiserated with control room operators over the challenges of handling summer heat but was told it was the shoulder months that caused the most anxiety. “They’re ready on those hot summer days when demand is screaming. … It’s those shoulder periods when the weather is volatile and the storms kick up that worry them,” Bonavia recounted.

Patton also praised the rollout of MISO’s extended locational marginal pricing (ELMP), which he said was responsible for about a 10% decrease in real-time revenue sufficiency guarantees paid out to market participants in the spring. However, Patton said he is still recommending that the RTO expand ELMP further to allow all generators with two-hour minimum run times to set prices, instead of MISO’s change, which added online resources with one-hour start-up times. MISO contends that the Monitor’s price-setting expansion would not be worth the expensive software change. (See “MISO Officially Expands ELMP,” MISO Market Subcommittee Briefs.)