A combined cycle power generation system (10) includes a steam turbine (14, 16, 18), a combustion system (12) including a compressor (24), a combustion chamber (26), a gas turbine (28), and a HRSG (20) to generate steam with energy from the combustion turbine. A flow line (60, 70) passes superheated steam into the combustion chamber. In an associated method a first source of power is provided via a combustion process having a variable reaction temperature in a first turbine. A second source of power is provided via a second turbine. Components of the system are placed in a mode of increasing power output with steam generated from the HRSG, during which a portion of the steam is provided into a combustion chamber associated with operation of the second turbine.