The main problem with ERCOT's grid stability isn't that they are using a lot of renewables so much as it is that ERCOT isn't interconnected with other big power systems in Texas's efforts to avoid federal oversight, as that Washington Post article indicates. They can't benefit much at all from buying power in other markets to make up for generation shortfalls lest they risk the feds making them do things they don't want to do. (On the flip side, they also can't sell their cheap renewable power into other markets as easily when they have excess generation capacity!)

There's an awful lot of schadenfreude that happens within the renewable energy and power production communities during serious power system events in ERCOT because they willingly suffer problems other power systems don't have to.