PJM will likely change its planning assumptions based on an analysis that found a strong correlation between wind chill indices and generator outages.
“Planning studies currently assume that forced outages are random and occur at a constant rate throughout the four seasons,” PJM’s Tom Falin told the Planning Committee last week. However, the analysis of generation outages from winters 2007/08 through 2012/13 found that the lower the wind chill, the more gas-fired capacity is lost to forced outages, including gas curtailments.
“We used to [consider] all unit forced outage rates as independent of each other, but we saw in January that they clearly are not. If you can’t get gas for one unit, you can’t get it for all units,” Falin said.
The analysis identified 9,244 MW of “chronically curtailed” gas plants — those that were curtailed an average of at least 12 hours per year. Jerry Bell of PJM explained that 2013/14 data was left out of the study because “we didn’t want to poison [the data] with the most recent winter.”
Under a worst-case scenario, which assumes the loss of all existing gas plants that were curtailed at least once over the last six winters and all “at-risk” future units (those likely to be “chronically curtailed” based on their pipeline supply), PJM could be forced to operate without 42,700 MW of gas capacity.
The analysis showed variability across zones. The ComEd zone, for example, had more than 2,600 MW of “chronically curtailed” gas generation while the JCPL zone had just 41 MW.
PJM officials said they will likely change their planning assumptions to recognize the increased risk of gas outages during extreme cold. The analysis may also result in new rules regarding the firmness of winter fuel supplies and calculation of winter Capacity Emergency Transfer Objectives and Capacity Emergency Transfer Limits.
“Clearly, the range of potential solutions is different for next winter than it is for 2019/20,” Vice President of Planning Steve Herling said. “Everything is on the table right now.”
Carl Johnson, of the PJM Public Power Coalition, said it may be necessary to develop both RTO-wide and zonal solutions. “In addition to studying why units were out, we should study why units weren’t out,” he said.