All major utility players upgraded their computer systems and tested them thoroughly in preparation for year 2000. In USA many of the utility companies switched over to their backup computers saving the main system in case something went wrong. As the clock ticked year 2000 no major incidents were reported. Except some clock synchronization minor problems everything went smoothly for all the energy companies.
Northeast utilities stated in a report that it is more likely that any power outages on Jan 1, 2000 will result from winter storm rather than the y2k computer bug.
This report gives fairly good idea about the preparation, drills and emergency plans the utility industry undertook.