COMBINED POWER GENERATION SYSTEM AND CONTROL METHOD THEREOF

Disclosed herein is a combined power generation system that includes a heat recovery steam generator configured to recover exhaust heat from a gas turbine to produce steam and including a high-pressure superheater and a reheater, a steam turbine operated by receiving the produced steam and including a high-pressure turbine, a medium-pressure turbine, and a low-pressure turbine, a condenser installed under the low-pressure turbine to condense steam, a high-pressure steam line for supplying the high-pressure turbine with the steam produced by the high-pressure superheater, a medium-pressure steam line for supplying the medium-pressure turbine with the steam that has passed through the high-pressure turbine, a high-pressure bypass line connected from the high-pressure steam line to the medium-pressure steam line, a reheat steam bypass line connected from downstream of the medium-pressure steam line to the condenser, and an additional high-pressure bypass line connected from the high-pressure steam line to the condenser.