The story in Houston is that it has been SO dry in Texas that salt is accumulating on the insulators on the transmission lines. ERCOT confirms that the outages are on company assets internal to the plant, and that other customers are not affected.
Usually the rain keeps the salt off. No rain for a long time here.
But for 3 different companies?
My employer installs outdoor electronic systems near salt water (east coast, west coast, Florida, Houston) and we are required to use equipment that will not be affected by salt. I'm surprised that refineries wouldn't have similar protection.