2nd grid alert in a week leads to rotating power outages in Alberta. What’s going on?

globalnews.ca:

Alberta Electric System Operator issued a grid alert for the province on Friday, and the provincial capital briefly faced rotating power outages — and it isn’t the first time this year Albertans have faced shortages.Just before 7 a.m., the AESO declared a grid alert due to tight supply.“Generation is slowly coming online, and we expect conditions to return to normal by 10 a.m.,” the non-profit organization posted on social media.Utility provider Epcor said around 9 a.m. that AESO had directed it to “help manage power consumption in the province” so rotating outages were rolling across Edmonton.Half an hour later, the outages stopped as the directive to conserve power had ended, but not before about 20,000 customers in Edmonton lost power at some point.Enmax Power also tweeted that a number of Calgary neighbourhoods could see power disruptions as a result of the AESO directive.Alberta’s electricity market is unique in Canada in that it is a for-profit, deregulated system.It pays generators only for the power they actually dispatch onto the grid and pays nothing for standby generating capacity.David Gray, former executive director of the Utility Consumer Advocate, said because Alberta operates as a real-time market, anything out of the ordinary brings the risk of knocking the system offline.“There’ve been a number of the thermal plants — either the refired coal plants that are now running on gas and the coal plant that’s left at Genesee — that have been having outages.