UPS or Stabilizer for LED TV
To cover a 15-second outage (power interruption) you need a UPS.

A basic UPS should protect your TV from surges, brownouts and overvoltages by switching to battery power (with a very short interruption to power) but during an extended brownout/overvoltage it will eventually cut power to the TV.

To cover extended brownouts or overvoltages, you need a line-interactive UPS.