Simple cycle configuration refers to the combustion turbine driving a generator with
the exhaust gases from the turbine flowing directly to the atmosphere. It is
thermodynamically based on the Brayton cycle.
The terms Brayton cycle and simple cycle are used interchangeably.
Combined cycle configuration refers to the combustion turbine driving a
generator where the exhaust gases from the turbine are directed into a heat
recovery steam generator (HRSG). The HRSG recovers a portion of the
exhaust heat energy by generating steam used by a steam turbine generator
(STG). The HRSG and STG are similar to components found in a conventional
thermal power plant which is referred to as a Rankine cycle.