The (lack of) power behind "Power Watch" warnings

Earlier this week state grid operators and the Public Utility Commission declared the lowest level of power emergency, a Power Watch, to encourage conservation. There have been a few this summer so far, which isn’t all that unusual. But three of them (including this week’s) have been because of unplanned power outages at power plants.
The Electric Reliability Council of Texas and the PUC generally don’t share who’s behind the outages. (It’s a big state, there are a lot of plants and mechanical/electrical failures can happen for many, many reasons.) But we’re always curious, so we checked around.
For the first Power Watch on June 25, the Lower Colorado River Authority’s Fayette Power Project near La Grange had one of its coal fired units under a “forced outage,” according to a spokeswoman, meaning it was down for an unplanned issue. (This plant was recently recognized by state environmental regulators for its good performance, BTW, and the lake used for cooling water is supposed to be good for fishing).
Also on June 25 the massive W.A. Parish power plant operated by NRG Energy South of Houston (you can see it’s huge stacks looming on the horizon on a clear day) tripped off that morning due to a “system voltage surge.”
In the early morning hours of July 9 Xcel Energy’s Harrington Station power plant near Amarillo had a fire in a fan unit that led to lower output from the plant (here’s a really lengthy report on it). Luminant’s Big Brown plant in Freestone County also had an unplanned outage that day.
We still don’t know which unplanned plant outages were behind this week’s Power Watch, but a unit of the Sandow power plant in Milam County, operated by Luminant, did have to report an emissions event to regulators because of an electrical ground.