Ercot does it at some point almost every summer. In 2011 DFW saw around 69 days straight of 100+ temps and we did rolling “brown outs”. It’s just an OCN, or operating condition notice, which is to make a public appeal to conserve energy. There are other things involved but that’s the main takeaway for the general public. It’s the first step when shorter than average generation is expected. Temperature is always the main driving factor. The Obama era war on coal, combined with increased use of unreliable wind and solar, will continue to make things worse. I’m not fanboying ercot by any means but they mainly just manage what’s available. If the generation isn’t there….point being we should focus on increasing reliable generation and taking the handcuffs off of nuclear.