Announcer

The Announcer plays a small part in Portal 2. He guides the player with pre-recorded messages through the facility early on in the game.

Most likely it is is an automated system created to monitor the Aperture lab complex prior GLaDOS, and lately left as a backup system to keep research going even during "circumstances of potentially apocalyptic significance". Designed to work in extreme and low power conditions, the system seems to have been automatically turned on