Abstract: Various embodiments include a system having: a computing device configured to control a power plant system including a steam turbine (ST), a gas turbine (GT), and a heat recovery steam generator (HRSG) fluidly connected with the ST and the GT, by performing actions including: obtaining data representing a target steam specific enthalpy in a bowl section of the ST; determining a current steam pressure at an outlet of the HRSG and a current steam temperature at the outlet of the HRSG; calculating an actual steam specific enthalpy in the bowl section of the ST based upon the current steam pressure at the outlet of the HRSG and the current steam temperature at the outlet the HRSG; and modifying a temperature of steam entering the ST in response to determining that the calculated actual steam specific enthalpy in the bowl section differs from the target steam specific enthalpy in the bowl section by a threshold.

Abstract: A steam turbine system and method of operating a steam turbine system including a steam generator coupled to a high pressure section and a low pressure section. The steam turbine system may further include to a first portion of a drive shaft coupled to the high pressure section and a clutching device for releasably coupling to a power generator coupled to the first portion of the drive shaft. The steam turbine system may also include a second portion of the drive shaft for coupling to the power generator coupled to the low pressure section. The method may be implemented using a controller of the steam turbine system.