A system configured to precisely control and/or modulate purge flow in a power plant system (e.g., a gas turbine) during operation is disclosed. In one embodiment, a system includes: at least one computing device adapted to control a purge flow in a gas turbine by performing actions comprising: obtaining operational data from the gas turbine; determining an inferred gas path pressure value for the gas turbine; determining an allowable purge flow for the gas turbine as a function of the operational data and the inferred gas path pressure value; and adjusting the purge flow based upon the allowable purge flow determination.