A system for controlling gas turbine output for a gas turbine power plant is disclosed herein. The power plant includes a gas turbine including a combustor downstream from a compressor, a turbine downstream from the combustor and an exhaust duct downstream from the outlet of the turbine. The exhaust duct receives exhaust gas from the turbine outlet. The system further includes an exhaust damper operably connected to a downstream end of the exhaust duct. The exhaust damper increases backpressure at the turbine outlet and restricts axial exit velocity of the exhaust gas exiting the turbine outlet when the exhaust damper is partially closed. A method for controlling gas turbine output is also provided herein.