I suppose, if you've already got a plc, or want one. You could use a small UPS and set up a bit to sense power loss. At power loss, use that bit to halt operation. And restore it when power returns.
Beware of safety factors. Like a person shutting down the machine by disconnecting power. Automatic restart could be dangerous.
Personally, I can't think of many operations with machinery where I'd like unattended start up.