Display apparatus, upgrade apparatus, control method thereof, and display system

Embodiments disclose a display apparatus including: an image processing unit which processes an image signal; a display unit which displays an image based on the processed image signal; a connection unit which connects to an upgrade apparatus which processes the image signal; a power supply unit which supplies power to each component of the display apparatus and the upgrade apparatus through the connection unit; and a first controller which controls the connection unit to receive the processed image signal from the upgrade apparatus when the upgrade apparatus is connected through the connection unit, wherein the power supply unit is controlled by the upgrade apparatus connected through the connection unit.